Computer Science

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Manufacturing an Exact Solution for 2D Thermochemical Mantle Convection Models
(Wiley Open Access [Commercial Publisher], American Geophysical Union [Society Publisher], Geochemical Society [Society Publisher], 2023) Trim, Sean; Butler, Samuel; McAdam, Shawn S.C.; Spiteri, Raymond
In this study, we manufacture an exact solution for a set of 2D thermochemical mantle convection problems. The derivation begins with the specification of a stream function corresponding to a non-stationary velocity field. The method of characteristics is then applied to determine an expression for composition consistent with the velocity field. The stream function formulation of the Stokes equation is then applied to solve for temperature. The derivation concludes with the application of the advection-diffusion equation for temperature to solve for the internal heating rate consistent with the velocity, composition, and temperature solutions. Due to the large number of terms, the internal heating rate is computed using Maple™, and code is also made available in Fortran and Python. Using the method of characteristics allows the compositional transport equation to be solved without the addition of diffusion or source terms. As a result, compositional interfaces remain sharp throughout time and space in the exact solution. The exact solution presented allows for precision testing of thermochemical convection codes for correctness and accuracy.
Exploiting High-Throughput Indoor Phenotyping to Characterize the Founders of a Structured B. napus Breeding Population
(Frontiers Media SA, 2022) Ebersbach, Jana; Khan, Nazifa Azam; McQuillan, Ian; Higgins, Erin; Horner, Kyla; Bandi, Venkat; Gutwin, Carl; Vail, Sally Lynne; Robinson, Steve J.; Parkin, Isobel
Phenotyping is considered a significant bottleneck impeding fast and efficient crop improvement. Similar to many crops, Brassica napus, an internationally important oilseed crop, suffers from low genetic diversity, and will require exploitation of diverse genetic resources to develop locally adapted, high yielding and stress resistant cultivars. A pilot study was completed to assess the feasibility of using indoor high-throughput phenotyping (HTP), semi-automated image processing, and machine learning to capture the phenotypic diversity of agronomically important traits in a diverse B. napus breeding population, SKBnNAM, introduced here for the first time. The experiment comprised 50 spring-type B. napus lines, grown and phenotyped in six replicates under two treatment conditions (control and drought) over 38 days in a LemnaTec Scanalyzer 3D facility. Growth traits including plant height, width, projected leaf area, and estimated biovolume were extracted and derived through processing of RGB and NIR images. Anthesis was automatically and accurately scored (97% accuracy) and the number of flowers per plant and day was approximated alongside relevant canopy traits (width, angle). Further, supervised machine learning was used to predict the total number of raceme branches from flower attributes with 91% accuracy (linear regression and Huber regression algorithms) and to identify mild drought stress, a complex trait which typically has to be empirically scored (0.85 area under the receiver operating characteristic curve, random forest classifier algorithm). The study demonstrates the potential of HTP, image processing and computer vision for effective characterization of agronomic trait diversity in B. napus, although limitations of the platform did create significant variation that limited the utility of the data. However, the results underscore the value of machine learning for phenotyping studies, particularly for complex traits such as drought stress resistance.
Don’t You Know That You’re Toxic: Normalization of Toxicity in Online Gaming
(ACM, 2021-05-06) Beres, Nicole A.; Frommel, Julian; Reid, Elizabeth; Mandryk, Regan; Klarkowski, Madison
Video game toxicity, endemic to online play, represents a pervasive and complex problem. Antisocial behaviours in online play directly harm player wellbeing, enjoyment, and retention—but research has also revealed that some players normalize toxicity as an inextricable and acceptable element of the competitive video game experience. In this work, we explore perceptions of toxicity and how they are predicted by player traits, demonstrating that participants reporting a higher tendency towards Conduct Reconstrual, Distorting Consequences, Dehumanization, and Toxic Online Disinhibition perceive online game interactions as less toxic. Through a thematic analysis on willingness to report, we also demonstrate that players abstain from reporting toxic content because they view it as acceptable, typical of games, as banter, or as not their concern. We propose that these traits and themes represent contributing factors to the cyclical normalization of toxicity. These findings further highlight the multifaceted nature of toxicity in online video games.
The Potential of Game Streaming as Exposure Therapy for Social Anxiety
(ACM, 2021-10-06) Frommel, Julian; Dechant, Martin; Mandryk, Regan
Social anxiety is a prevalent problem that affects many people with varying severity; digital exposure therapy—which involves controlled exposure to simulations of feared social situations alongside cognitive restructuring—can help treat patients with anxieties. However, the need to personalize exposure scenarios and simulate audiences are barriers to treating social anxieties through digital exposure. In this paper, we propose game streaming as an exposure therapy paradigm for social anxiety, supporting it with data from two studies. We first propose a framework describing requirements for exposure therapy and how game streaming can fulfill them. We select demand and performance visibility from these characteristics to showcase how to manipulate them for experiences of gradual exposure. With Study 1, we provide evidence for these characteristics and support for the framework by showing that a game’s demand affected expected fear of streaming games. In Study 2, we show that the prospect of streaming led to elevated fear, a necessary property for effective exposure therapy. Further, we show that the effect of streaming on expected fear was similar for participants who can be considered socially anxious. These findings provide evidence for the essential effect of exposure therapy, which serves as a first step towards the validation of streaming as a social anxiety treatment. Our paper provides an initial, important step towards a novel, broadly applicable, and widely accessible digital approach for the treatment of social anxiety.
Videogame Play and Wellbeing Among a First Episode Psychosis Population
(Association for Computing Machinery, 2021-09) Johnson, Daniel; Gore-Jones, Victoria; Dark, Frances; Parker, Stephen; Foley, Sharon; Mandryk, Regan L.
With ongoing interest in the relationship between videogame and mental health alongside recent focus on gaming’s role in coping with stressful life events, we sought to explore the relationship between videogame play and wellbeing among people experiencing their first episode of psychosis. Specifically, we aimed to explore the associations between videogame play and wellbeing among consumers of a first episode psychosis (FEP) service and further to compare their motivations for play, need satisfaction, passion for play and wellbeing to a control group. A sample of 88 people experiencing FEP (57 who played videogames and 31 who did not) and a control sample of 46 (all of whom played videogames) completed a survey containing a range of questionnaires related to the variables of interest. Key findings include that among those experiencing FEP, people who played videogames reported better wellbeing outcomes than those who did not. Among participants who played videogames, the FEP sample reported lower levels of need satisfaction through gaming, lower levels of harmonious passion, higher levels of external types of motivation and lower levels of internal types of motivation for play than the control group. Finally, the relationships between passion orientation (both harmonious and obsessive) and psychological distress were stronger in the control group than the FEP sample, suggesting that passion for gaming may be less influential on wellbeing for those experiencing FEP.
Mediating Asymmetries in Family Communication: Supporting the eInclusion of Older Adults
(Springer International Publishing, 2015-08-02) Gutierrez, Francisco J; Ochoa, Sergio F; Vassileva, Julita
Background: The rise of mobile Web-based technologies has diversified the mechanisms used by people to socialize, which results in issues in family communication. Among these concerns, the reluctance of older adults to use digital media may cause them social isolation, leading to negative effects in their physical and mental health. Objective: This paper aims to formalize a model to mediate asymmetries in cross-generational communication and support the eInclusion of older adults. Methods: We conducted semi-structured interviews to the members of 20 cross-generational families. Following the grounded theory approach, we identified emerging themes regarding asymmetries in family communication practices when older adults are involved. We then derived and formalized computer-based mediation strategies using a model-driven engineering approach. Results: We identified three main sources of asymmetries: (1) implicit family agreements in terms of social interaction, (2) capability and preferences for using particular media, and (3) unbalanced socio-affective coupling between the involved parties. The proposed model addresses these asymmetries and provides strategies to coordinate the communication effort of family members with their elders. Conclusions: By using the proposed model, designers of software that supports family communities can conceive effective mechanisms to coordinate and mediate social communication among cross-generational family members through digital means. This allows the elderly to show a better reaction to digital media, thus facilitating their acceptance and appropriation of information technologies.
Providing awareness, explanation and control of personalized filtering in a social networking site
(Springer US, 2016-02-01) Vassileva, Julita; Nagulendra, Sayooran
Social networking sites (SNSs) have applied personalized filtering to deal with overwhelmingly irrelevant social data. However, due to the focus of accuracy, the personalized filtering often leads to “the filter bubble” problem where the users can only receive information that matches their pre-stated preferences but fail to be exposed to new topics. Moreover, these SNSs are black boxes, providing no transparency for the user about how the filtering mechanism decides what is to be shown in the activity stream. As a result, the user’s usage experience and trust in the system can decline. This paper presents an interactive method to visualize the personalized filtering in SNSs. The proposed visualization helps to create awareness, explanation, and control of personalized filtering to alleviate the “filter bubble” problem and increase the users’ trust in the system. Three user evaluations are presented. The results show that users have a good understanding about the filter bubble visualization, and the visualization can increase users’ awareness of the filter bubble, understandability of the filtering mechanism and to a feeling of control over the data stream they are seeing. The intuitiveness of the design is overall good, but a context sensitive help is also preferred. Moreover, the visualization can provide users with better usage experience and increase users’ trust in the system.
Does gamification work for boys and girls?: An exploratory study with a virtual learning environment
(ACM New York, NY, USA ©2015, 2015-04-13) Pedro, Lais Z; Lopes, Aparecida MZ; Prates, Bruno G; Vassileva, Julita; Isotani, Seiji
The development and use of Virtual Learning Environments (VLE) has increased considerably over the past decades. Following that trend, many research findings have shown the benefits of using VLE during the learning process. Nevertheless, there are important problems that hinder their use requiring further investigation. Among them, one of the main problems is the inappropriate use of these systems by students. The boredom, lack of interest, monotony, lack of motivation, among other factors, ultimately causes students to behave inappropriately and lead them to a lower performance. In this context, the proposed study investigates whether it is possible to reduce undesirable behaviors and increase performance of students through the use of game mechanics (i.e. gamification). We develop a VLE, E-Game, that can turn on/off several game mechanics, such as points, badges, levels and so on. A case study was conducted with two groups of students to investigate their behavior during their interaction with E-Game with and without gamification. The results indicate that the gamification implemented by E-Game contributed to improve student performance in the case of boys. Yet, improvement was not observed in the case of girls. Furthermore, it was not possible to conclude whether the use of gamification helps to prevent inappropriate student behavior, and therefore, further studies and experiments are needed.
How do you feel when you see a list of prices? the interplay among price dispersion, perceived risk and initial trust in Chinese C2C market
(Elsevier, 2015-07-31) Wu, Kewen; Vassileva, Julita; Noorian, Zeinab; Zhao, Yuxiang
The issues of trust fraud, product genuineness and price dispersion jointly make Chinese C2C buyers difficult to identify trustworthy sellers with a low price. Little is known about the generation of initial trust when buyers search products and receive lists of widely ranged prices. This study proposes a theoretical model to explain how price dispersion interacts with other factors in C2C purchase, such as initial trust, perceived risk, perceived value and purchase intention. Product type is considered as a moderator. 261 students were invited in a survey-based experiment. The results from PLS analysis show that price dispersion negatively affects perceived value, whilst, positively affects perceived risk, which further influences perceived value negatively. Price dispersion also negatively influences initial trust through perceived risk. Moreover, the negative effects of price dispersion are stronger when buyers purchase high-touch products.
Mapping Wiki User Contribution Types to Motivations for Participation: A Case Study
(2015) Adewoyin, Oluwabunmi; Wu, Kewen; Vassileva, Julita
Different classifications of Wiki editor have been proposed. However, so far there has been no mapping between user classes based on their contributions and their motivations, which can be useful to design persuasive functions in wiki systems to increase participation. In this study, we attempt to bridge this gap by developing a customized MediaWiki system, used by 10 senior undergraduate students for their coursework. The participants were classified into three editors' classes and mapped to their motivation factors, using the system data and the results from the exit questionnaire.
Complexity or simplicity? Designing product pictures for advertising in online marketplaces
(Pergamon, 2016-01-31) Wu, Kewen; Vassileva, Julita; Zhao, Yuxiang; Noorian, Zeinab; Waldner, Wesley; Adaji, Ifeoma
In online marketplaces, many sellers highlight product and service information directly within product pictures for advertising purposes. Such a strategy increases the visual complexity of the picture and provides more information to support buyers’ judgment. However, when other sellers adopt the same method, a given picture will not be conspicuous enough to be noticed. To address this issue, the concept of complexity contrast is introduced. No prior attention has been paid in literature to the interplay between visual complexity and complexity contrast. This research proposes a theoretical model to explain the influences of visual complexity and complexity contrast on buyers’ pleasantness in shopping, while perceptual and conceptual fluency act as mediators. Results from a lab experiment suggest an entangled effect of complexity contrast and visual complexity, indicating that buyers are influenced more by the conspicuousness of a product picture, rather than the information conveyed by a product picture when it is visually overwhelming.
Exploiting the Use of Wikis to Support Collaborative Writing: A Case Study of an Undergraduate Computer Science Class
(Springer International Publishing, 2015-09-22) Adewoyin, luwabunmi; Wu, Kewen; Vassileva, Julita
Use of wikis in education reflects a shift in the education paradigm from lecture and individual homework-based to a paradigm emphasizing student engagement and the construction of knowledge through collaboration and peer-help. Existing research work on the use of wiki in collaborative writing had given mixed results. The goals of this research are to investigate whether wiki supports learning of writing and argumentation skills, and whether the students are motivated to use it and see it as a useful learning tool. Our participants comprise ten senior undergraduate students of a Computer Science class, who engaged in collaborative writing using wiki for four weeks. Their contributions were graded by a designated TA. The grades assigned to both their final articles and individual contributions, and the wiki logs were analyzed to determine the quality and volume of their weekly contributions, while feedback was taken from them using questionnaire to sample their perception of the use of wiki in writing. Our results showed that the use of wiki is helpful in improving their writing skill. However, participants are not happy with the further use of wiki in their course work. Also, we found that they require extrinsic motivation, in form of feedback (grades) from the TA and acceptance of their contribution by their peers, to increase their participation in wiki writing.
Ethics of scientific peer review: Are we judging or helping the review recipients?
(IEEE, 2014-09-08) Adewoyin, Oluwabunmi; Vassileva, Julita
Traditionally, ethics of a profession or organization are laid down by their pioneers, or subtly emerge over time as the organization advance. Getting conversant to these ethics requires teaching new or upcoming professionals, in order to avoid any form of misconduct, either deliberately or unknowingly. Peer review has been used as a quality control measure in the scientific community to ensure that only novel, high-quality and significant research work can be published. Typically, experienced and well respected scientists are selected to review the work of their peers or other upcoming scientists. Ideally, people who ethically qualify as reviewers, should have high reputation in terms of their ability to give objective and well-informed judgement, write constructive and helpful critique in a timely manner and, are honest and open in revealing any conflict of interest that may exist. The key objectives of peer review are two fold: 1) summative - to assess the quality of scholarly work, and 2) formative - to provide constructive feedback and thus, to mentor authors to become both better researchers, and better writers.
Factors Influencing User’s Attitude to Secondary Information Sharing and Usage
(SRCE-Sveučilišni računski centar, 2015-09-01) Iyilade, Johnson; Vassileva, Julita; Orji, Rita
The increasing availability of enormous data about users online, along with availability of sophisticated tools and technology to store, aggregate, and analyze data for secondary use has raised concerns about how to balance the opportunity for secondary use of data with the need to protect the user privacy that may result from harmful use. To develop a privacy protection mechanism that is useful and meets the expectations and needs of the user, it is important to understand users’ attitude to privacy and secondary information sharing and usage of his/her data. While several studies have investigated factors influencing users’ attitude to privacy in primary data collection context, none of the existing studies have provided an understanding of user perception and attitude to privacy in secondary context. To fill this gap, this work has identified five factors that are important in a secondary usage context and carried out a study on their influence on users’ perception with respect to how their data is shared for secondary use. The main contribution of this paper is an understanding of factors influencing user decisions about privacy in secondary context, which can assist both technology designers and policy makers in the development of appropriate privacy protection that meets the needs and expectations of the user.
Identifying Opportunities to Support Family Caregiving in Chile
(ACM New York, NY, USA ©2016, 2016-05-07) Gutierrez, Francisco; Vassileva, Julita; Ochoa, Sergio
Once older adults become less self-sufficient, one or more adult children often assume the role of family caregiver. Unfortunately, this situation is usually perceived as stressful by caregivers. To better understand this process, we interviewed intergenerational triads: older adults, their adult children acting as caregivers, and their grandchildren. The study results show that the commitment of caregivers is quite strong regardless of the place where they live. In addition, the gender of older adults and caregivers affects the dynamics and complexity of the process. Through this study we aim to identify opportunities to support family caregiving, respecting the preexisting relations, attitudes, needs, and expectations of the involved stakeholders.
Effect of Different Implicit Social Networks on Recommending Research Papers
(ACM New York, NY, USA ©2016, 2016-07-13) Alotaibi, Shaikhah; Vassileva, Julita
Combining social network information with collaborative filtering recommendation algorithms has successfully reduced some of the drawbacks of collaborative filtering and increased the accuracy of recommendations. However, all approaches in the domain of research paper recommendation have used explicit social relations that users have initiated which has the problem of low recommendation coverage. We argued that the available data in social bookmarking Web sites such as CiteULike or Mendeley could be exploited to connect similar users using implicit social connections based on their bookmarking behavior. In this paper, we proposed three different implicit social networks-readership, co-readership, and tag-based and we compared the recommendation accuracy of several recommendation algorithms using data from the proposed social networks as input to the recommendation algorithms. Then, we tested which implicit social network provides the best recommendation accuracy. We found that, for the most part, the social recommender is the best algorithm and that the readership network with reciprocal social relations provides the best information source for recommendations but with low coverage. However, the co-readership network provide good recommendation accuracy and better user coverage of recommendation.
Gender Difference in the Credibility Perception of Mobile Websites: A Mixed Method Approach
(ACM New York, NY, USA, 2016-07-13) Oyibo, Kiemute; Vassileva, Julita; Sahabi Ali, Yusuf
To persuade people to buy a product or service online, they must be visually convinced and attracted to use the sales website. Thus, there is need to understand how different user groups perceive various designs of websites for better adaptation. A lot of research has shown that users' judgment of the credibility of a website is critical to its success. However, in the mobile domain, little has been done empirically to 1) investigate users' credibility perception of a website; and 2) how it changes as the user interface (UI) design is systematically altered. This paper bridges this gap by carrying out sentiment and statistical analyses of users' perceptions of four systematically modified mobile websites among 285 subjects from North America, Africa and Asia. The results show that mobile website design affects the perception of its credibility, with 1) females being more critical and sensitive to UI changes than males; and 2) the grid-layout website design preferred to the list-layout website design by both genders. The study contributes to knowledge in three ways. First, it provides a concise model for understanding users' UI perceptions, expectations and gender differences. Second, it presents important findings that will enable a gender-based mobile website adaptation. Third, it provides a set of empirically backed guidelines for mobile web design.
Modelling User Collaboration in Social Networks Using Edits and Comments
(ACM New York, NY, USA, 2016-07-13) Adaji, Ifeoma; Vassileva, Julita
Research has shown that in Q&A social networks, collaboration between respondents results in quality answers. Since good answers are required to keep any Q&A social network active, it is important to understand the characteristics of these collaborations and the collaborators. In this paper, we investigate how Stack Overflow promotes collaboration by allowing users to edit existing questions and answers in order to improve them. Using over 40,000 answer posts, our study reveals that collaboration in answer posts is not a function of achievement earned in terms of badges, as most edits associated with "best answer" rewards were posted by users who have not earned any answer badge. Our study further shows that posts that earned the "best answer" reward have more comments than those that did not. This study though, work in progress, can aid developers in implementing collaboration strategies in social networks that work.
How buyers perceive the credibility of advisors in online marketplace: review balance, review amount and misattribution
(Springer Berlin Heidelberg, 2015-02-12) Vassileva, Julita; Wu, Kewen; Noorian, Zeinab; Adaji, Ifeoma
In an online marketplace, buyers rely heavily on reviews posted by previous buyers (referred to as advisors). The advisor’s credibility determines the persuasiveness of reviews. Much work has addressed the evaluation of advisors’ credibility based on their static profile information, but little attention has been paid to the effect of the information about the history of advisors’ reviews. We conducted three sub-studies to evaluate how the advisors’ review balance (proportion of positive reviews) affects the buyer’s judgement of advisor’s credibility (e.g., trustworthiness, expertise). The result of study 1 shows that advisors with mixed positive and negative reviews are perceived to be more trustworthy, and those with extremely positive or negative review balance are perceived to be less trustworthy. Moreover, the perceived expertise of the advisor increases as the review balance turns from positive to negative; yet buyers perceive advisors with extremely negative review balance as low in expertise. Study 2 finds that buyers might be more inclined to misattribute low trustworthiness to low expertise when they are processing high number of reviews. Finally, study 3 explains the misattribution phenomenon and suggests that perceived expertise has close relationship with affective trust. Both theoretical and practical implications are discussed.

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