Browsing by Author "Chen, Yan"

Now showing 1 - 18 of 18
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    Balancing fear and confidence: A strategic approach to mitigating human risk in cybersecurity
    Galletta, Dennis F.; Moody, Gregory D.; Lowry, Paul Benjamin; Willison, Robert; Boss, Scott; Chen, Yan; Luo, Xin; Pienta, Daniel A.; Polak, Peter; Schuetze, Sebastian; Thatcher, Jason (2025)
    Despite technological advances, cybersecurity breaches persist, with human actions often being the weakest link. Educational programs and policies have been ineffective in reducing threats, as shown by rising trend data breaches and costs, averaging $9.48 million in 2023. The growing threat persists despite the plethora of tools and techniques, indicating a need for a strategic shift. Drawing on interviews with C-level IS executives and earlier experimental research, this paper advocates for greater care in warning users about security dangers, and simultaneously building their confidence in their ability to improve their cybersecurity safety. Managers must carefully balance their communications, instilling appropriate concern without causing excessive fear or negativity.
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    CFlow: Supporting Semantic Flow Analysis of Students' Code in Programming Problems at Scale
    Zhang, Ashley; Tang, Xiaohang; Oney, Steve; Chen, Yan (ACM, 2024-07-09)
    Introductory programming courses have been growing rapidly, now enrolling hundreds or thousands of students. In such large courses, it can be overwhelmingly difficult for instructors to understand class-wide problem-solving patterns or issues, which is crucial for improving instruction and addressing important pedagogical challenges. In this paper, we propose a technique and system, CFlow, for creating understandable and navigable representations of code at scale. CFlow is able to represent thousands of code samples in a visualization that resembles a single code sample. CFlow creates scalable code representations by (1) clustering individual statements with similar semantic purposes, (2) presenting clustered statements in a way that maintains semantic relationships between statements, (3) representing the correctness of different variations as a histogram, and (4) allowing users to navigate through solutions interactively using semantic filters. With a multi-level view design, users can navigate high-level patterns, and low-level implementations. This is in contrast to prior tools that either limit their focus on isolated statements (and thus discard the surrounding context of those statements) or cluster entire code samples (which can lead to large numbers of clusters—for example, if there are 𝑛 code features and 𝑚 implementations of each, there can be 𝑚𝑛 clusters). We evaluated the effectiveness of CFlow with a comparison study, found participants using CFlow spent only half the time identifying mistakes and recalled twice as many desired patterns from over 6,000 submissions.
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    Characterization of Bacillus Spore Membrane Proteomes and Investigation of Their Roles in the Spore Germination Process
    Chen, Yan (Virginia Tech, 2014-09-23)
    Components of the bacterial spore germination apparatus are crucial for survival and for initiation of infection by some pathogens. While some components of the germination apparatus are well conserved in spore-forming species, such as the spoVA operon, each species may possess a different and possibly unique germinant recognition mechanism. The significance of several individual proteins in the germination process has been characterized. However, the mechanisms of how these proteins perform their functions and the network connecting these proteins in the complete germination process are still a mystery. In this study, we characterized a Bacillus subtilis superdormant spore population and investigated the abundance of 11 germination-related proteins. The relative quantities of these proteins in dormant, germinating and superdormant spores suggested that variation in the levels of proteins, other than germinant receptor proteins may result in superdormancy. Specifically, variation in the abundance of the GerD lipoprotein may contribute to heterogeneity of spore germination rates. Spore membrane proteomes of Bacillus anthracis and B. subtilis were characterized to generate a candidate protein list that can be further investigated. Proteins that were not previously known to be spore-associated were identified, and many of these proteins shared great similarity in both Bacillus species. A significant number of these proteins are implicated in functions that play major roles in spore formation and germination, such as amino acid or inorganic ion transport and protein fate determination. By analyzing the in vivo and in vitro activity of HtrC, we proved that the protease is responsible for YpeB proteolytic processing at specific sites during germination. However, without HtrC present in the spore, other proteases appear to degrade YpeB at a reduced rate. The activity of purified HtrC in vitro was stimulated by a relatively high concentration of Mn²⁺ or Ca²⁺ ions, but the mechanism behind the stimulation is not clear. We also demonstrated that YpeB and SleB, in the absence of their partner protein, were degraded by unknown proteases other than HtrC during spore formation. Identification and characterization of these unknown proteases would be a future direction for revealing the roles of proteases in spore germination.
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    DevCoach: Supporting Students in Learning the Software Development Life Cycle at Scale with Generative Agents
    Wang, Tianjia; Ramanujan, Ramaraja; Lu, Yi; Mao, Chenyu; Chen, Yan; Brown, Chris (ACM, 2024-07-09)
    Supporting novice computer science students in learning the software development life cycle (SDLC) at scale is vital for ensuring the quality of future software systems. However, this presents unique challenges, including the need for effective interactive collaboration and access to diverse skill sets of members in the software development team. To address these problems, we present “DevCoach”, an online system designed to support students learning the SDLC at scale by interacting with generative agents powered by large language models simulating members with different roles in a software development team. Our preliminary user study results reveal that DevCoach improves the experiences and outcomes for students, with regard to learning concepts in SDLC’s “Plan and Design” and “Develop” phases.We aim to use our findings to enhance DevCoach to support the entire SDLC workflow by incorporating additional simulated roles and enabling students to choose their project topics. Future studies will be conducted in an online Software Engineering class at our institution, aiming to explore and inspire the development of intelligent systems that provide comprehensive SDLC learning experiences to students at scale.
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    DiLogics: Creating Web Automation Programs with Diverse Logics
    Pu, Kevin; Yang, Jim; Yuan, Angel; Ma, Minyi; Dong, Rui; Wang, Xinyu; Chen, Yan; Grossman, Tovi (ACM, 2023-10-29)
    Knowledge workers frequently encounter repetitive web data entry tasks, like updating records or placing orders. Web automation increases productivity, but translating tasks to web actions accurately and extending to new specifications is challenging. Existing tools can automate tasks that perform the same logical trace of UI actions (e.g., input text in each field in order), but do not support tasks requiring different executions based on varied input conditions.We present DiLogics, a programming-by-demonstration system that utilizes NLP to assist users in creating web automation programs that handle diverse specifications. DiLogics first semantically segments input data to structured task steps. By recording user demonstrations for each step, DiLogics generalizes the web macros to novel but semantically similar task requirements. Our evaluation showed that non-experts can effectively use DiLogics to create automation programs that fulfill diverse input instructions. DiLogics provides an efficient, intuitive, and expressive method for developing web automation programs satisfying diverse specifications.
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    DUET: Distinct but United Event-based Timelines
    Luu, Andy (Virginia Tech, 2025-01-03)
    Through innovations in sensors and storage, event-based data collection has increased significantly in recent years. Personal security cameras allow users to collect event data in their homes, Google Maps allows users to view places they have been throughout the day, and web browsers collect a history of the sites users visit. Despite the innovations in event-based data collection, the Graphical User Interfaces (GUIs) designed for these systems have not changed for years. Many applications stick to a linear timeline to display the events, leading to large downtime gaps when sparse events occur throughout the day. However, linear timelines create a natural sense of temporal perception since users can easily tell what time of day certain events occur. Our project seeks to find a balance between the natural temporal perception that linear timelines offer and improving the usability of visualizing event-based data using timelines. Through our design, users will be able to leverage the simple temporal perception that a linear timeline provides and avoid unnecessary searching to locate specific events. By seamlessly integrating a linear timeline with density visualizations and a timeline of events, we aim to allow users to search and view events easily. To evaluate our interface, we conducted two usability studies, first with specialists who view security camera information often and then with all individuals. Our findings inform the design of future event-based timeline visualizations.
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    An Exploratory Study of Involving Parents in E-book Joint Reading with Voice Agents
    Vargas Diaz, Daniel Alfredo (Virginia Tech, 2024-06-06)
    Parent-child interactions during joint reading play an important role in young children's cognitive and language development. However, contemporary digital book formats---such as e-books or audiobooks---often overlook the role of the parent in reading the text, by either dubbing voice narration over it or reading it aloud automatically. With the advancement and prevalence of voice-based conversational artificial intelligence (AI) agents, AI reading an e-book emerges as a novel reading experience, yet reducing the role of parents in the reading process similarly. When the reading experience becomes less of a joint activity between children and parents, the potential benefits children can gain from reading may diminish. In this study involving 11 parent-child pairs, we aimed to explore how voice agents (VAs) could be used to create an interactive digital space to 1) promote parental engagement in joint e-book reading with children and 2) enhance parents' and children's joint reading experiences. We developed and evaluated TaleMate, an interactive joint reading app that allows parents and children ages 3-6 years to assign different AI voices to the characters from a book while enabling parents to embody one of the characters to read the book with the voice agents. We found that the system supported children's engagement and story comprehension. Parents reported that they found value in the interactivity of the system and enjoyed a participatory, joint reading experience, where both they and their children could choose which characters to embody. These findings offer insights into design considerations for researchers interested in developing applications that facilitate collaborative reading experiences involving parents, children, and voice agents.
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    Generative Co-Learners: Enhancing Cognitive and Social Presence of Students in Asynchronous Learning with Generative AI
    Wang, Tianjia; Wu, Tong; Liu, Huayi; Brown, Chris; Chen, Yan (ACM, 2025-01-10)
    Cognitive presence and social presence are crucial for a comprehensive learning experience. Despite the flexibility of asynchronous learning environments to accommodate individual schedules, the inherent constraints of asynchronous environments make augmenting cognitive and social presence particularly challenging. Students often face challenges such as a lack of timely feedback and support, an absence of non-verbal cues in communication, and a sense of isolation. To address this challenge, this paper introduces Generative Co-Learners, a system designed to leverage generative AI-powered agents, simulating co-learners supporting multimodal interactions, to improve cognitive and social presence in asynchronous learning environments.We conducted a study involving 12 student participants who used our system to engage with online programming tutorials to assess the system’s effectiveness. The results show that by implementing features to support textual and visual communication and simulate an interactive learning environment with generative agents, our system enhances the cognitive and social presence in the asynchronous learning environment. These results suggest the potential to use generative AI to support student learning and transform asynchronous learning into a more inclusive, engaging, and efficacious educational approach.
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    Helping job seekers prepare for technical interviews by enabling context-rich interview feedback
    Lu, Yi (Virginia Tech, 2024-06-11)
    Technical interviews have become a popular method for recruiters in the tech industry to assess job candidates' proficiency in both soft skills and technical skills as programmers. However, these interviews can be stressful and frustrating for interviewees. One significant cause of the negative experience of technical interviews was the lack of feedback, making it difficult for job seekers to improve their performance progressively by participating in technical interviews. Although there are open platforms like Leetcode that allow job seekers to practice their technical proficiency, resources for conducting mock interviews to practice soft skills like communication are limited and costly to interviewees. To address this, we investigated how professional interviewers provide feedback if they were conducting a mock interview and the difficulties they face when interviewing job seekers by running mock interviews between software engineers and job seekers. With the insights from the formative studies, we developed a new system for technical interviews aiming to help interviewers conduct technical interviews with less cognitive load and provide context-rich feedback. An evaluation study on the usability of using our system to conduct technical interviews further revealed the unresolved cognitive loads of interviewers, underscoring the requirements for further improvement to facilitate easier interview processes and enable peer-to-peer interview practices.
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    HtrC Is Involved in Proteolysis of YpeB during Germination of Bacillus anthracis and Bacillus subtilis Spores
    Bernhards, Casey B.; Chen, Yan; Toutkoushian, Hannah; Popham, David L. (American Society for Microbiology, 2014-11-10)
    Bacterial endospores can remain dormant for decades yet can respond to nutrients, germinate, and resume growth within minutes. An essential step in the germination process is degradation of the spore cortex peptidoglycan wall, and the SleB protein in Bacillus species plays a key role in this process. Stable incorporation of SleB into the spore requires the YpeB protein, and some evidence suggests that the two proteins interact within the dormant spore. Early during germination, YpeB is proteolytically processed to a stable fragment. In this work, the primary sites of YpeB cleavage were identified in Bacillus anthracis, and it was shown that the stable products are comprised of the C-terminal domain of YpeB. Modification of the predominant YpeB cleavage sites reduced proteolysis, but cleavage at other sites still resulted in loss of full-length YpeB. A B. anthracis strain lacking the HtrC protease did not generate the same stable YpeB products. In B. anthracis and Bacillus subtilis htrC mutants, YpeB was partially stabilized during germination but was still degraded at a reduced rate by other, unidentified proteases. Purified HtrC cleaved YpeB to a fragment similar to that observed in vivo, and this cleavage was stimulated by Mn2+ or Ca2+ ions. A lack of HtrC did not stabilize YpeB or SleB during spore formation in the absence of the partner protein, indicating other proteases are involved in their degradation during sporulation.
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    Improving Rainfall Index Insurance: Evaluating Effects of Fine-Scale Data and Interactive Tools in the PRF-RI Program
    Ramanujan, Ramaraja (Virginia Tech, 2024-06-04)
    Since its inception, the Pasture, Rangeland, and Forage Rainfall Index (PRF-RI) insurance program has issued a total of $8.8 billion in payouts. Given the program's significance, this thesis investigates methodologies to help improve it. For the first part, we evaluated the impact of finer-scale precipitation data on insurance payouts by comparing how the payout distribution differs between the program's current dataset and the finer-scale precipitation dataset by creating a simulated scenario where all parameters are constant except the rainfall index computed by the respective dataset. The analysis for Texas in 2021 revealed that using the finer-scale dataset to compute the rainfall index would result in payouts worth $27 million less than the current dataset. The second part of the research involved the development of two interactive decision-support tools: the "Next-Gen PRF" web tool and the "AgInsurance LLM" chatbot. These tools were designed to help users understand complex insurance parameters and make informed decisions regarding their insurance policies. User studies for the "Next-Gen PRF" tool measured usability, comprehension decision-making efficiency, and user experience, showing that it outperforms traditional methods by providing insightful visualizations and detailed descriptions. The findings suggest that using fine-scale precipitation data and advanced decision-support technologies can substantially benefit the PRF-RI program by reducing spatial basis risk and promoting user education, thus leading to higher user engagement and enrollment.
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    In situ investigation of stress-induced martensitic transformation in granular shape memory ceramic packings
    Rauch, Hunter A.; Chen, Yan; An, Ke; Yu, Hang Z. (2019-04-15)
    Stress-induced martensitic transformation can occur in granular shape memory materials when individual particles experience high stresses and transform from a high-symmetry austenite phase to a low symmetry martensite phase. This involves a highly heterogeneous distribution of the driving force and very low mechanical constraint for martensite nucleation, so the transformation behavior can be dramatically different from the well-documented case of monolithic solids. In this work, we investigate the stress-induced martensitic transformation in granular shape memory ceramic packings, which consist of single-crystal micro-particles of ZrO2-12 at%CeO2 and ZrO2-15 at%CeO2. Through in situ neutron diffraction, we study how the phase fraction, lattice strain, and integral peak broadness evolve during external loading, unloading, and subsequent heating. Several peculiar features are discovered, including (i) a continuous mode of transformation with a wide range of transformation loads, (ii) co-evolution of the packing structure, contact deformation, and martensitic transformation, and (iii) a strong correlation between the peak broadening and the transformed phase fraction. In addition, we show the first direct evidence of reversible stress-induced martensitic transformation in granular materials. We finally discuss the mechanism for martensite nucleation and growth in granular packings and show how that leads to the observed transformation characteristics.
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    Levels of Germination Proteins in Bacillus subtilis Dormant, Superdormant, and Germinating Spores
    Chen, Yan; Ray, W. Keith; Helm, Richard F.; Melville, Stephen B.; Popham, David L. (PLOS, 2014-04-21)
    Bacterial endospores exhibit extreme resistance to most conditions that rapidly kill other life forms, remaining viable in this dormant state for centuries or longer. While the majority of Bacillus subtilis dormant spores germinate rapidly in response to nutrient germinants, a small subpopulation termed superdormant spores are resistant to germination, potentially evading antibiotic and/or decontamination strategies. In an effort to better understand the underlying mechanisms of superdormancy, membrane-associated proteins were isolated from populations of B. subtilis dormant, superdormant, and germinated spores, and the relative abundance of 11 germination-related proteins was determined using multiplereaction-monitoring liquid chromatography-mass spectrometry assays. GerAC, GerKC, and GerD were significantly less abundant in the membrane fractions obtained from superdormant spores than those derived from dormant spores. The amounts of YpeB, GerD, PrkC, GerAC, and GerKC recovered in membrane fractions decreased significantly during germination. Lipoproteins, as a protein class, decreased during spore germination, while YpeB appeared to be specifically degraded. Some protein abundance differences between membrane fractions of dormant and superdormant spores resemble protein changes that take place during germination, suggesting that the superdormant spore isolation procedure may have resulted in early, non-committal germination-associated changes. In addition to low levels of germinant receptor proteins, a deficiency in the GerD lipoprotein may contribute to heterogeneity of spore germination rates. Understanding the reasons for superdormancy may allow for better spore decontamination procedures.
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    TimeLink: Visualizing Diachronic Word Embeddings and Topics
    Williams, Lemara Faith (Virginia Tech, 2024-06-11)
    The task of analyzing a collection of documents generated over time is daunting. A natural way to ease the task is by summarizing documents into the topics that exist within these documents. The temporal aspect of topics can frame relevance based on when topics are introduced and when topics stop being mentioned. It creates trends and patterns that can be traced by individual key terms taken from the corpus. If trends are being established, there must be a way to visualize them through the key terms. Creating a visual system to support this analysis can help users quickly gain insights from the data, significantly easing the burden from the original analysis technique. However, creating a visual system for terms is not easy. Work has been done to develop word embeddings, allowing researchers to treat words like any number. This makes it possible to create simple charts based on word embeddings like scatter plots. However, these methods are inefficient due to loss of effectiveness with multiple time slices and point overlap. A visualization method that addresses these problems while also visualizing diachronic word embeddings in an interesting way with added semantic meaning is hard to find. These problems are managed through TimeLink. TimeLink is proposed as a dashboard system to help users gain insights from the movement of diachronic word embeddings. It comprises a Sankey diagram showing the path of a selected key term to a cluster in a time period. This local cluster is also mapped to a global topic based on an original corpus of documents from which the key terms are drawn. On the dashboard, different tools are given to users to aid in a focused analysis, such as filtering key terms and emphasizing specific clusters. TimeLink provides insightful visualizations focused on temporal word embeddings while maintaining the insights provided by global topic evolution, advancing our understanding of how topics evolve over time.
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    VizGroup: An AI-assisted Event-driven System for Collaborative Programming Learning Analytics
    Tang, Xiaohang; Wong, Sam; Pu, Kevin; Chen, Xi; Yang, Yalong; Chen, Yan (ACM, 2024-10-13)
    Programming instructors often conduct collaborative learning activities, like Peer Instruction, to foster a deeper understanding in students and enhance their engagement with learning. These activities, however, may not always yield productive outcomes due to the diversity of student mental models and their ineffective collaboration. In this work, we introduce VizGroup, an AI-assisted system that enables programming instructors to easily oversee students’ real-time collaborative learning behaviors during large programming courses. VizGroup leverages Large Language Models (LLMs) to recommend event specifications for instructors so that they can simultaneously track and receive alerts about key correlation patterns between various collaboration metrics and ongoing coding tasks. We evaluated VizGroup with 12 instructors in a comparison study using a dataset collected from a Peer Instruction activity that was conducted in a large programming lecture. The results showed that VizGroup helped instructors effectively overview, narrow down, and track nuances throughout students’ behaviors.
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    VizPI: A Real-Time Visualization Tool for Enhancing Peer Instruction in Large-Scale Programming Lectures
    Tang, Xiaohang; Chen, Xi; Wong, Sam; Chen, Yan (ACM, 2023-10-29)
    Peer instruction (PI) has shown significant potential in facilitating student engagement and collaborative learning. However, the implementation of PI for large-scale programming lectures has proven challenging due to difficulties in monitoring student engagement, discussion topics, and code changes. This paper introduces VizPI, an interactive web tool that enables instructors to conduct, monitor, and assess PI for programming exercises in real-time. With features that visualize the progress of student discussions and code submissions, VizPI allows for more effective oversight of PI activities and the provision of personalized feedback at scale. Our work aims to transform the pedagogical approach to PI in programming education, making it more engaging and adaptable to student needs.
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    VizProg: Identifying Misunderstandings by Visualizing Students' Coding Progress
    Zhang, Ashley; Chen, Yan; Oney, Steve (ACM, 2023-04-19)
    Programming instructors often conduct in-class exercises to help them identify students that are falling behind and surface students’ misconceptions. However, as we found in interviews with programming instructors, monitoring students’ progress during exercises is difficult, particularly for large classes. We present VizProg, a system that allows instructors to monitor and inspect students’ coding progress in real-time during in-class exercises. VizProg represents students’ statuses as a 2D Euclidean spatial map that encodes the students’ problem-solving approaches and progress in real-time. VizProg allows instructors to navigate the temporal and structural evolution of students’ code, understand relationships between code, and determine when to provide feedback. A comparison experiment showed that VizProg helped to identify more students’ problems than a baseline system. VizProg also provides richer and more comprehensive information for identifying important student behavior. By managing students’ activities at scale, this work presents a new paradigm for improving the quality of live learning.
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    When Less Can Be More: Evaluating the Impact of Animated and Interactive Demonstrations in Voice-Assisted Counting Games for Young Children
    Karunaratna, Sulakna Binoka Kumarihamy (Virginia Tech, 2025-01-17)
    Early experiences with counting form a critical foundation for children's numeracy development. Despite the increasing use of voice assistants in young children's math learning, the effectiveness of different levels of demonstration—animated and interactive—accompanied by these assistants remains unclear. This study examines how different demonstrations in touchscreen devices, combined with voice assistants, supported children's developing counting skills. We developed a tablet counting game for children aged 2-4 years, incorporating voice assistant counting. In a user study with 32 children, we compared two conditions (animated and interactive demonstrations), with each condition also being evaluated against a baseline. We found that animated demonstrations improved math performance compared to the baseline, while interactive demonstrations did not. These findings suggest that counting with voice assistants has the potential to support early counting experiences and highlight the importance of designing educational technology with appropriate levels of demonstration to engage young learners without increasing cognitive overload.