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关键词： Manifolds   Prediction algorithms   Kernel   Sparse matrices   Robustness   Computer science   Data models   Robust auto-weighted label propagation (ALP)   semisupervised classification (SSC)   triple matrix recovery (TMR)  

摘要： The graph-based semisupervised label propagation (LP) algorithm has delivered impressive classification results. However, the estimated soft labels typically contain mixed signs and noise, which cause inaccurate predictions due to the lack of suitable constraints. Moreover, the available methods typically calculate the weights and estimate the labels in the original input space, which typically contains noise and corruption. Thus, the encoded similarities and manifold smoothness may be inaccurate for label estimation. In this article, we present effective schemes for resolving these issues and propose a novel and robust semisupervised classification algorithm, namely the triple matrix recovery-based robust auto-weighted label propagation framework (ALP-TMR). Our ALP-TMR introduces a TMR mechanism to remove noise or mixed signs from the estimated soft labels and improve the robustness to noise and outliers in the steps of assigning weights and predicting the labels simultaneously. Our method can jointly recover the underlying clean data, clean labels, and clean weighting spaces by decomposing the original data, predicted soft labels, or weights into a clean part plus an error part by fitting noise. In addition, ALP-TMR integrates the auto-weighting process by minimizing the reconstruction errors over the recovered clean data and clean soft labels, which can encode the weights more accurately to improve both data representation and classification. By classifying samples in the recovered clean label and weight spaces, one can potentially improve the label prediction results. Extensive simulations verified the effectivenss of our ALP-TMR.

关键词： Computer Science Education   Curriculum   Schools   digital competency  

摘要： This paper explores the rationales underpinning the introduction of Computer Science (CS) into school curricula and examines the ways in which educational systems have responded to these growing calls. In outlining the possible ways that educational systems can respond to this demand, the paper makes use of a conceptual framework through which the various possibilities for the provision of CS in school curricula can be categorised. The paper analyses and discusses possible modes of provision identifying the benefits and drawbacks of different approaches. Through this development, the paper aims to raise wider questions about the long-term positioning of CS within the curriculum and draws particular attention to the need for greater consideration of provision at lower secondary level.

关键词： Subgoal learning   instructional design   Computer Science Principles   K-12  

摘要： The subgoal learning framework has improved performance for novice programmers in higher education, but it has only started to be applied and studied in K-12 (primary/secondary). Programming education in K-12 is growing, and many international initiatives are attempting to increase participation, including curricular initiatives like Computer Science Principles and non-profit organizations like *** . Given that subgoal learning is designed to help students with no prior knowledge, we designed and implemented subgoals in the introduction to programming unit in ***'s Computer Science Principles course. The redesigned unit includes subgoal-oriented instruction and subgoal-themed pre-written comments that students could add to their programming activities. To evaluate efficacy, we compared behaviors and performance of students who received the redesigned subgoal unit to those receiving the original unit. We found that students who learned with subgoals performed better on problem-solving questions but not knowledge-based questions and wrote more in open-ended response questions, including a practice Performance Task for the AP exam. Moreover, at least one-third of subgoal students continued to use the subgoal comments after the subgoal-oriented instruction had been faded, suggesting that they found them useful. Survey data from the teachers suggested that students who struggled with the concepts found the subgoals most useful. Implications for future designs are discussed.

摘要： The potential scarring effects of long-term youth unemployment and social disengagement have for many years challenged policymakers to develop successful and sustainable interventions. © 2020, The Author(s).

关键词： Computer science   Quantum information   Technology  

摘要： Trapped-ion systems are gaining momentum in the quest to make a commercial quantum computer.

关键词： Universal Serial Bus   Authentication   Password   Servers   Computer science   Biometrics (access control)   Authentication   hash function   provable security   random oracle model   USB device  

摘要： Universal Serial Bus (USB) is widely used, for example to facilitate hot-swapping and plug-and-play. However, USB ports can be exploited by an adversary to extract private or personal data from the connected devices. Hence, a number of organizations and workplaces have prohibited their employees from using USB devices, and there have been efforts to design secure USB storage device schemes to more effectively resist different known security attacks. However, designing such schemes is challenging. For example, in this article we revisit the Wei et al.'s scheme, and demonstrate that it is vulnerable to attacks such as password guessing and user impersonation. We also explain that the scheme does not verify the correctness of user's input in the login phase, which is another design flaw. Then, we present an improved scheme and prove it secure in the random oracle model.

关键词： Measurement   Adaptation models   Optimization   Computational modeling   Learning systems   Training   Computer science   Domain adaptation   LogDet metric   second-order statistics alignment  

摘要： Domain adaptation has proven to be successful in dealing with the case where training and test samples are drawn from two kinds of distributions, respectively. Recently, the second-order statistics alignment has gained significant attention in the field of domain adaptation due to its superior simplicity and effectiveness. However, researchers have encountered major difficulties with optimization, as it is difficult to find an explicit expression for the gradient. Moreover, the used transformation employed here does not perform dimensionality reduction. Accordingly, in this article, we prove that there exits some scaled LogDet metric that is more effective for the second-order statistics alignment than the Frobenius norm, and hence, we consider it for second-order statistics alignment. First, we introduce the two homologous transformations, which can help to reduce dimensionality and excavate transferable knowledge from the relevant domain. Second, we provide an explicit gradient expression, which is an important ingredient for optimization. We further extend the LogDet model from single-source domain setting to multisource domain setting by applying the weighted Karcher mean to the LogDet metric. Experiments on both synthetic and realistic domain adaptation tasks demonstrate that the proposed approaches are effective when compared with state-of-the-art ones.

摘要： Background: CS4All is an $81 million private-public investment aimed at creating the necessary infrastructure to provide computer science experiences to all New York City public-school students by 2025. Purpose: In this paper, we examine the history of the CS4All initiative and document the network of actors and their relationships in the system such that we can understand how this reform is enacted, how it might be reactive to external contexts and pressures, and how the structure and pathways of this particular social network might inform similar efforts elsewhere. Research Design: To structure our analysis of CS4All, we first examine the most recent historic example of a large-scale curricular reform-Man: A Course of Study (MACOS). By reflecting on the network structure of CS4All in light of the design, enactment, and eventual failure of MACOS, we can identify potential pain points and opportunities in CS4All's 10-year effort. We conducted interviews with core members of the CS4All initiative and examined available public records to construct and analyze a social network of key CS4All stakeholders, other actors, processes, and institutions. Conclusions: In our analysis of the CS4All social network, we document how well-connected individuals simultaneously mobilized government resources and grassroots enthusiasm to create the conditions necessary for the initiation of this massive curricular reform effort, and describe the current pathways in place for decision making and resource distribution. Comparing the history and structure of the CS4All initiative to Man: A Course of Study-a failed nationwide curricular reform in the 1960s-we find that CS4All's centralized decision-making process and failure to create and distribute high quality formative assessment tools may lead to challenges to adoption. However, explicit efforts to solicit input from and communicate initiative values to the large diversity of stakeholders throughout NYC, as well as the innovation of a d

关键词： Electronic textiles   physical computing systems   novice programming   diversity  

摘要： Electronic textiles, which integrate computation with fabrics through a redesigned interface of microcontrollers, sensors, and actuators, have expanded possibilities not only for engineering, fashion, and human-computer interaction but also for computer science education itself. While individual studies involving electronic textiles have shown promise to diversify participation, raise interest, and deepen learning in computing, especially for female students, we recognized a need to synthesize findings across studies to understand the overall contribution of electronic textiles to computing education. In this article, we report our findings from a meta-synthesis of 64 educational electronic textiles studies to answer the following questions in computing: (1) Did electronic textiles broaden access and participation? (2) How did electronic textiles support learners' interests and sustain participation? (3) What and how did students learn from electronic textile projects? Our meta-synthesis revealed that although electronic textiles successfully broadened access, supported learners' interests, and introduced basic computational concepts to novice learners, questions around equitable participation and deeper disciplinary engagement persist. We discuss directions for future design and research efforts to explore the full potential of e-textiles in computer science education.

关键词： Computer science   Engineering   Cardiology   Medical imaging   Biomedical engineering   Radiology   Clinical research   Contour segmentation   Topographic watershed segmentation   Short-axis 5D cardiac sequences   MRI   Medical decision making  

摘要： A comparative study has been depicted between the contour and topographic watershed segmentation approach for short-axis 5D cardiac sequences with MRI for medical decision. The fifth dimension has been defined as the excitation of pixels based on the gray scale around the myocardium without consideration of the morphological structure of the heart in 3D and fourth dimension (time). Three patients were performed the first is healthy, the second has a genetic disease, and the third had a heart failure syndrome for a dimension ROI = 150mm, average age is 54 years old, and mean of weight = 86 kg. A contouring and watershed segmentation algorithm for a sample of 63 Cine Fiesta MRI sequences for short-axis cuts with Matlab and its in-box toolbox complements was implemented. For a healthy patient 13.4% tolerance rate for the estimation of the stroke fraction, 6.4% for a patient with genetic disease, 8.7% error rate for a patient with heart failure symptom. The results show that the regurgitation fraction by the contour approach for a patient case with symptom of the presence of a genetic disease is 0.0335% for an aortic valve, 0.248% for a mitral valve, an error rate 0.16% for estimating this parameter for the aortic orifice with the watershed segmentation approach. In return, for a patient with suspected heart failure (stenosis or regurgitation) the regurgitation fraction is estimated by 0% for aortic valve, 1.49 e (+) (03)% for a mitral valve, an error rate 11.76% compared to the watershed segmentation approach. The results are validated clinically. The Optimization of the topographic watershed approach with mutual information was simulated for the extraction of measurements (ejection fraction, regurgitation rate) within the left ventricle for three patient types (healthy, genetic pathology and heart failure). The results are considered interesting compared to the clinical assessment.