Measuring and Modeling Group Dynamics in Open-Source Software Development: A Tensor Decomposition Approach

Many open-source software projects depend on a few core developers, who take over both the bulk of coordination and programming tasks. They are supported by peripheral developers, who contribute either via discussions or programming tasks, often for a limited time. It is unclear what role these peripheral developers play in the programming and communication efforts, as well as the temporary task-related sub-groups in the projects. We mine code-repository data and mailing-list discussions to model the relationships and contributions of developers in a social network and devise a method to analyze the temporal collaboration structures in communication and programming, learning about the strength and stability of social sub-groups in open-source software projects. Our method uses multi-modal social networks on a series of time windows. Previous work has reduced the network structure representing developer collaboration to networks with only one type of interaction, which impedes the simultaneous analysis of more than one type of interaction. We use both communication and version-control data of open-source software projects and model different types of interaction over time. To demonstrate the practicability of our measurement and analysis method, we investigate 10 substantial and popular open-source software projects and show that, if sub-groups evolve, modeling these sub-groups helps predict the future evolution of interaction levels of programmers and groups of developers. Our method allows maintainers and other stakeholders of open-source software projects to assess instabilities and organizational changes in developer interaction and can be applied to different use cases in organizational analysis, such as understanding the dynamics of a specific incident or discussion.

Digilantism, discrimination, and punitive attitudes: A digital vigilantism model

In this article, I propose and apply a digital vigilantism model to a specific incident that occurred in Mexico, where the death of two innocent people was filmed through Facebook Live. Using a mixed methods approach and content analysis, I analyzed digilante Facebook posts ( N = 942) coding gender, digital vigilantism categories, discriminatory comments, and punitive attitudes aimed at the perpetrators and the inciter of the lynching. The categories include investigating, blaming, or rebuking, while the discriminatory comments include classism, racism, homophobia, and body-shaming. I coded the punitive attitudes distinguishing four categories: non-physical punishment (calling for God’s wrath and the guilty conscience of the targets), legal sanction, death, and other punishment. The findings reveal the key role gender played in digilantism: females tend to conduct more investigations and low level attacks (blaming) than males, but males tend to perpetrate more harsh attacks (rebuking) than females. The most popular punitive attitude is calling for the death of targets, revealing tensions between legal sanctions and digilantes’ desired punishment. This study suggests the presence of different expressions of discrimination and reasons to engage in digilantism, encompassing both legal and illegal behavior deployed in a mainstream social media platform such as Facebook.

The Interaction of Structural Factors and Diffusion in Social Unrest: Evidence from the Swing Riots

Studies of the causes of social unrest typically focus on structural factors or diffusion. This article demonstrates the importance of considering their interaction and reveals a complex interplay between the two. This interaction is examined in the context of the English Swing riots of 1830–1831, in which it is possible to observe the structural factors relevant to each specific incident; this is often impossible when analyzing more recent cases of unrest. The authors find that the riots were triggered by economic factors and that diffusion more than tripled the direct effect of changes in local factors. Economic factors and the presence of potential riot leaders made an area more susceptible to the incoming diffusion of riots. The ways in which structural factors and diffusion interact is relevant to both historical and recent instances of social unrest.

Predictive Validity of a Functional Movement Screen in Professional Basketball Players

Background and objectives: Striking a balance between maximizing performance and preventing injury remains elusive in many professional sports. The purpose of this study was to assess the relative risk of non-contact injuries in professional basketball players based on predictive cut scores on the Functional Movement Screen™ (FMS). Materials and Methods: Thirty-two professional basketball players from the National Basketball Association (NBA) and Women’s National Basketball Association (WNBA) participated in this study. This observational pilot cohort study assessed and scored each participant using the FMS during training camp. Each athlete was then tracked throughout the season while recording the number, type, and time lost due to injuries. Possible exposures, actual exposures, and exposures missed due to non-contact injury (NCI) for each athlete were calculated and then used to determine the crude and specific incident rates for exposures missed due to NCI per 1000 exposures. Results: Linear regression models were used to evaluate the predictive ability of the FMS score for total missed exposures, NCI, and CI missed exposures. In all models, the FMS total score failed to attain significance as a predictor (p > 0.05). FMS scores ranged from 5 to 18. The recommended cut score of 14 showed a sensitivity of 0.474 and a specificity of 0.750. The cut score of 15 showed the best combination, exhibiting a sensitivity of 0.579 and specificity of 0.625. A total of 5784 exposures to NCI were possible for the men and women combined, and 681 possible exposures were missed. Of these, 23.5% were due to NCI, 16.5% were due to contact injuries (CI), and 60% were due to illnesses and personal reasons. Conclusions: The FMS proved to be a measure that was not associated with any injury measure in this sample of professional basketball players, suggesting the instrument lacks predictive validity in this population.

Risk Factors for NON-HPV16/18 Cervical Infections and Associated Lesions Among HPV-DNA-Negative Women Vaccinated Against HPV16/18 in the Costa Rica Vaccine Trial (CVT)

Background Factors that lead human papillomavirus (HPV) infections to persist and progress to cancer are not fully understood, especially among vaccinated women. We evaluated co-factors for acquisition, persistence and progression of non-HPV16/18 infections in a cohort of HPV-vaccinated women. Methods We analyzed 2,153 18-25-year-old women randomized to the HPV-vaccine arm of CVT. Women were HPV-DNA-negative for all types at baseline and followed for ~11 years. Acquisition was a type-specific cervical infection not present/detected at the previously scheduled visit. Persistence was a type-specific incident infection that persisted for ≥1-year with no intervening negatives. Progression of persistent incident infections to CIN2+ was based on histological findings by expert pathologists. GEE methods were used to account for correlated observations. Time-dependent factors evaluated were age, sexual behavior, marital status, hormonal-related factors, number of full-term pregnancies (FTP), smoking behavior, and baseline-BMI. Results 1,777 incident oncogenic non-HPV16/18 infections were detected in 12,292 visits (average 0.14 infections per visit). Age and sexual behavior-related variables were associated with oncogenic non-HPV16/18 acquisition. 26% of incident infections persisted for ≥1-year. None of the factors evaluated were statistically associated with persistence of oncogenic non-HPV16/18 infections. Risk of progression to CIN2+ increased with increasing age (p-trend=0.001), injectable contraceptives use [relative risk 2.61 (95%CI 1.19–5.73) ever vs. never] and increasing FTP (p-trend=0.034). Conclusion In a cohort of HPV16/18-vaccinated women, age and sexual behavior variables are associated with acquisition of oncogenic non-HPV16/18 infections, no notable factors are associated with persistence of acquired oncogenic non-HPV16/18 infections, and age, parity and hormonally-related exposures are associated with progression to CIN2+.

Identifying hazards at residential and commercial pools: An interactive session

This special joint session with shared interest from multiple technical groups (Children’s Issues Technical Group, Forensics Professional Group, and Safety Technical Group) provides audience members with an opportunity to discuss multiple case examples of fatal incidents involving children and pools. Participants will first hear several examples of human factors forensic analyses of different cases. The audience will then perform a safety audit for a pool owner, working in teams, identifying potential hazards and ways the owner can mitigate the hazards. Teams will present the findings of the safety analysis. After team presentations, the facts of an incident involving the subject pool will be presented to determine if their safety analysis recommendations could have prevented the specific incident. This session will emphasize the broad application of human factors for forensic incidents involving children and pools as well as safety analyses to educate owners and potentially help to prevent incidents.

Sharpening Justice Through DisCrit: A Contrapuntal Analysis of Education

Calls for justice-centered education approaches have gained traction over the years. Yet given the entrenched inequities that disproportionately harm multiply-marginalized students of color, it is evident that they remain incomplete. Using a specific incident as our launching point, we explore current conceptualizations of justice through a disability critical race theory (DisCrit) contrapuntal reading of four prolific intellectuals whose work is often not in conversation: Nancy Fraser, Iris Marion Young, Mia Mingus, and Talia Lewis. We query, (a) How does the author conceptualize justice? (b) How does the author consider difference in relationships to justice? and (c) How does the author (re)imagine potential ways to remedy injustice? By recognizing connectedness and maintaining tensions framed within DisCrit, this article enumerates expansive conceptualizations of justice through centering multiply-marginalized communities of color.

Characterization of Optically-Reconfigurable Metasurfaces by a Free Space Microwave Bistatic Technique

Microwave performance extraction of optically-controlled squared frequency-selective surface (FSS) structures printed on highly resistive (HR) silicon substrate are presented, from a innovative bistatic microwave photonic characterization technique operating in the 40 to 60 GHz frequency range, commonly used for radar cross section (RCS) measurements. According to typical physical photon absorption phenomenon occurring in photoconductive materials, these structures demonstrate experimentally a bandpass filtering frequency response cancellation through reflection coefficient measurements, under specific incident collective illumination in the Near-infrared region (NIR). This behaviour is attributed to their microwave surface impedance modification accordingly to the incident optical power, allowing ultrafast reconfigurability of such devices by optics

Algorithm for Tracing Train Delays to Incident Causes

Knowledge of the root cause(s) of delays in transit networks has obvious value; it can be used to direct resources toward mitigation efforts and measure the effectiveness of those efforts. However, delays with indirect causes can be difficult to attribute, and may be assigned to broad categories that indicate “overcrowding,” incorrectly naming heavy ridership, train congestion, or both, as the cause. This paper describes a methodology to improve such incident assignments using historical train movement and incident data to determine if there is a root-cause incident responsible for the delay. It is intended as first step toward improved, data-driven delay recording to help time-strapped dispatchers investigate incident impacts. This methodology considers a train’s previous trip and when it arrived at the terminal to begin its next trip, as well as en route running times and dwell times. If the largest source of delay can be traced to a specific incident, that incident is suggested as the cause. For New York City Transit (NYCT), this methodology reassigns about 7% of trains originally without a root cause identified by dispatchers. Its results are provided to NYCT’s Rail Control Center staff via automated daily reports which, along with other improvements to delay recording procedures, has reduced these “overcrowding” categories from making up 38% of all delays in early 2018 to only 28% in 2019. The results confirm both that it is possible to improve delay cause diagnoses with algorithms and that there are delays for which both humans and algorithms find it difficult to determine a cause.