Video-based Analysis Research Articles

Video-Based Analysis of a Smart Lighting Warning System for Pedestrian Safety at Crosswalks

Video-Based Analysis of a Smart Lighting Warning System for Pedestrian Safety at Crosswalks

Video Content Analysis for Detection of Road Traffic Congestion Pattern: An Optimized YOLOv8 Based Approach

This paper presents a new approach to Video Content Analysis (VCA) with a specific focus on detecting and analyzing road traffic congestion patterns. The implemented methodology deploys the YOLOv8 (You Only Look Once) object detection framework, which has been optimized to accurately and efficiently identify road traffic objects within video streams. The primary goal is to improve traditional VCA systems by capturing and understanding complex road congestion scenarios. This research develops a customized YOLO model optimized specifically for road traffic analysis. The optimization process addresses the challenges inherent in real-world traffic scenarios including variations in lighting conditions, diverse vehicle types and dynamic traffic flow patterns. The developed model seeks to enable robust and real-time detection of congestion-related events such as heavy congestion and normal congestion thereby contributing to improved traffic management and overall road safety. Moreover, the paper explores the integration of advanced techniques for congestion pattern analysis including vehicle detection, tracking, and counting. The combination of these features facilitates a comprehensive understanding of traffic dynamics and congestion evolution over time. The proposed approach is trained and evaluated on benchmark datasets and real-world video footage to assess its performance. Experimental results demonstrate the effectiveness of the optimized YOLOv8-based approach in accurately detecting and analyzing road traffic congestion patterns. The system exhibits promising capabilities in handling diverse and challenging scenarios thereby serving as a valuable tool for intelligent transportation systems, urban planning and traffic management. This research significantly contributes to the advancement of video-based traffic analysis, providing a robust solution for monitoring and mitigating congestion-related challenges on road networks.

Physical demands of collegiate basketball practice: a preliminary report on novel methods and metrics.

Knowing the specific physical demands of basketball players can provide useful information for clinical decision making when rehabilitating athletes following injury. The purpose of this observational study was to describe the physical demands of basketball play at the Division I collegiate level using video-based time-motion analysis and introduce a time-efficient alternative method of quantifying demands. Eleven NCAA Division I basketball players (6M, 5F; 4 guards, 4 centers, 3 forwards) participated in the study. Video footage was collected from four practices (2 men's, 2 women's) and used to quantify the types and frequencies of player movements based on definitions from seminal work. A second and simpler method was also used to classify movement. A two-way ANOVA was used to assess significant differences in movement by team (men's, women's) and position (guard, forward, center). There were significant differences in counts of stand/walk (p < 0.001), jog (p = 0.012), run (p = 0.001), stride/sprint (p = 0.04), and medium-intensity shuffling (p < 0.001) per minute and proportion of practice time spent in bodyweight (p < 0.001) or above-bodyweight (p < 0.001) loading between teams. There were significant differences for jog (p = 0.001) and transition (p = 0.07) rates across positions. Position and team are important considerations for rehabilitation and return-to-sport clearance. Quantification of these demands can be reliably acquired through video analysis using a simplified method (estimated foot load) or using traditional methods of movement classification and counts, particularly when applying descriptors that better capture the current style of play.

ArmSpy++: Enhanced PIN Inference through Video-based Fine-grained Arm Posture Analysis

As one of the most common ways for user authentication, Personal Identification Number (PIN), due to its simplicity and convenience, has suffered from plenty of side-channel attacks, which pose a severe threat to people’s privacy and property. The success of existing attacks is usually built upon the premise of no occlusion between the attacker and the victim’s hand gesture, but it increases the difficulty of launching the attack and the possibility of exposure. To overcome such limitation, we propose ArmSpy++, an improved video-assisted PIN inference attack built upon our previous research, ArmSpy. Specifically, ArmSpy++ employs new modules to leverage more features like the keystroke-induced elbow bending, wrist speed variation, and the spatial relationship between different arm joints, to correctly detect Keystrokes. ArmSpy++ delves into the perspective relationship and natural typing habits to ensure a high success rate of PIN inference. We also re-designed the inferred PIN pattern coordination mechanism to accurately deduce the PINs. By using a pre-trained HigherHRNet model for posture estimation ArmSpy++ eliminates the necessity of additional training. The extensive experiments demonstrate that ArmSpy++ can achieve over \(83.1\% \) average accuracy with 3 attempts and even \(92.5\% \) for some victims, indicating the severity of the threat posed by ArmSpy++.

Characteristics of motion signal profiles of tonic-clonic, tonic, hyperkinetic, and motor seizures extracted from nocturnal video recordings.

In this study, characteristics of signal profiles formed by motion, oscillation, and sound signals were analyzed to evaluate generalizability and variability in a single patient setting (intra-patient variability) and between patients (inter-patient variability). As a secondary objective, the effect of brivaracetam intervention on signal profiles was explored. Patient data included 13 hyperkinetic seizures, 65 tonic seizures, 13 tonic-clonic seizures, and 138 motor seizures from 11 patients. All patients underwent an 8-week monitoring, and after a 3-week baseline, brivaracetam was initiated. Motion, oscillation, and sound features extracted from the video were used to form signal profiles. Variance of signals was calculated, and combined median and quartile visualizations were used to visualize the results. Similarly, the effect of intervention was visualized. Hyperkinetic motion signals showed a rapid increase in motion and sound signals without oscillations and achieved low intra-patient variance. Tonic component created a recognizable peak in motion signal typical for tonic and tonic-clonic seizures. For tonic seizures, inter-patient variance was low. Motor signal profiles were varying, and they did not form a generalizable signal profile. Visually recognizable changes were observed in the signal profiles of two patients. Video-based motion signal analysis enabled the extraction of motion features characteristic for different motor seizure types which might be useful in further development of this system. Tonic component formed a recognizable seizure signature in the motion signal. Hyperkinetic and motor seizures may have not only significantly different motion signal amplitude but also overlapping signal profile characteristics which might hamper their automatic differentiation. Motion signals might be useful in the assessment of movement intensity changes to evaluate the treatment effect. Further research is needed to test generalizability and to increase reliability of the results.

Multilingual and multimodal methods to examining the situated communication among deaf children and their caregivers

ABSTRACT This paper discusses methodologies for examining the multilingual language experiences of young deaf children that are sensitive to different cultural contexts of childhood, caregiving and language practices. We argue that in the context of early support, the combined use of situated multilingual and multimodal approaches to examine and assess individual language resources can provide rich and reliable information about individual communicative repertoires in their given context. This approach extends commonly used monolingual and unimodal research and assessment tools that lack the inclusivity of reach and granularity of analysis needed to inform contextually appropriate early intervention for multilingual and migrant deaf learners. We illustrate the potential of these methods using case study examples from multimodal video-based and ethnographic data gathering and analysis techniques deployed across three projects in different multilingual contexts, in Ghana and the UK. We use these case studies to examine the methodological choices, challenges and opportunities of researching different multilingual environments in culturally sensitive ways as a basis for supporting and assessing the language and communication development of young deaf children in multilingual and migrant contexts. We discuss how the resulting new knowledge base can extend Euro-Western epistemologies that are currently leading models of early intervention and support.

Video-Based Performance Analysis in Pituitary Surgery - Part 2: Artificial Intelligence Assisted Surgical Coaching

Superior surgical skill improves surgical outcomes in endoscopic pituitary adenoma surgery. Video-based coaching programs, pioneered in professional sports, have shown promise in surgical training. In this study, we developed and assessed a video-based coaching program using artificial intelligence (AI) assistance. An AI-assisted video-based surgical coaching was implemented over 6months with the pituitary surgery team. The program consisted of 1) monthly random video analysis and review; and 2) quarterly 2-hour educational meetings discussing these videos and learning points. Each video was annotated for surgical phases and steps using AI, which improved video interactivity and allowed the calculation of quantitative metrics. Primary outcomes were program feasibility, acceptability, and appropriateness. Surgical performance (via modified Objective Structured Assessment of Technical Skills) and early surgical outcomes were recorded for every case during the 6-month coaching period, and a preceding 6-month control period. Beta and logistic regression were used to assess the change in modified Objective Structured Assessment of Technical Skills scores and surgical outcomes after the coaching program implementation. All participants highly rated the program's feasibility, acceptability, and appropriateness. During the coaching program, 63 endoscopic pituitary adenoma cases were included, with 41 in the control group. Surgical performance across all operative phases improved during the coaching period (P < 0.001), with a reduction in new postoperative anterior pituitary hormone deficit (P= 0.01). We have developed a novel AI-assisted video surgical coaching program for endoscopic pituitary adenoma surgery - demonstrating its viability and impact on surgical performance. Early results also suggest improvement in patient outcomes. Future studies should be multicenter and longer term.

Abstract We047: Enhanced Vascularization in hPSC-derived Cardiac Organoids by Dynamic Culture

Introduction: Human pluripotent stem cells (hPSC)-derived cardiac organoids (COs) have gained increasing interest in biotechnology due to their characteristics like diverse cardiovascular cell types, 3D complex structure, and function that recapitulates the human heart in early development. However, current methods for vascularizing COs are not systematic and robust. Hypothesis: We hypothesize that culturing hPSC-derived COs dynamically will further enhance vascularization in COs. Materials and Methods: Two conditions were created to compare vascularization in COs: 1) dynamic culturing (Dyn) and 2) static culturing (St). Firstly, hPSCs were cultured for two days in ultra-low attachment plates to develop spheroids. The spheroids were then transferred to pillar plates followed by direct cardiac differentiation the next day. Live-cell imaging was used to monitor the process of vascularization for up to 16 days and the corresponding fluorescence intensity of each cell type from its reporter expression was analyzed. The cardiac function was measured by video-based contractility analysis. Data were presented as mean ± standard error of the mean (SEM). The student’s t-test was used for the statistical analysis. Results: Cardiomyocytes (CMs) and endothelial cells (ECs) were imaged on pillars under the two conditions as shown in Fig. 1A . Successful cardiac differentiation was present, displaying hPSC-CM contraction on day 12 and onwards. Higher intensity values of hPSC-CMs under Dyn were observed in all four days compared to St as shown in Figs. 1B&amp;C . The hPSC-ECs intensity displayed greater intensity values compared to St, demonstrating enhanced vascularization in VCOs due to the active Dyn as shown in Figs. 1D&amp;E . The functionality was improved in Dyn as indicated with higher contraction velocity as shown in Fig. 1F. Conclusion: This study demonstrates the effects of incorporating dynamic culture for enhancing cardiogenesis and vasculogenesis in hPSC-derived COs. The enhanced hPSC-VCOs hold promise for studying early cardiovascular development, congenital heart disease modeling, and drug screening and discovery.

Video-Based Performance Analysis in Pituitary Surgery—Part 1: Surgical Outcomes

Endoscopic pituitary adenoma surgery has a steep learning curve, with varying surgical techniques and outcomes across centers. In other surgeries, superior performance is linked with superior surgical outcomes. This study aimed to explore the prediction of patient-specific outcomes using surgical video analysis in pituitary surgery. Endoscopic pituitary adenoma surgery videos from a single center were annotated by experts for operative workflow (3 surgical phases and 15 surgical steps) and operative skill (using modified Objective Structured Assessment of Technical Skills [mOSATS]). Quantitative workflow metrics were calculated, including phase duration and step transitions. Poisson or logistic regression was used to assess the association of workflow metrics and mOSATS with common inpatient surgical outcomes. 100 videos from 100 patients were included. Nasal phase mean duration was 24minutes and mean mOSATS was 21.2/30. Mean duration was 34minutes and mean mOSATS was 20.9/30 for the sellar phase, and 11minutes and 21.7/30, respectively, for the closure phase. The most common adverse outcomes were new anterior pituitary hormone deficiency (n= 26), dysnatremia (n= 24), and cerebrospinal fluid leak (n= 5). Higher mOSATS for all 3 phases and shorter operation duration were associated with decreased length of stay (P= 0.003 &P < 0.001). Superior closure phase mOSATS were associated with reduced postoperative cerebrospinal fluid leak (P < 0.001), and superior sellar phase mOSATS were associated with reduced postoperative visual deterioration (P= 0.041). Superior surgical skill and shorter surgical time were associated with superior surgical outcomes, at a generic and phase-specific level. Such video-based analysis has promise for integration into data-driven training and service improvement initiatives.

Accuracy of Kinovea-based kinematic gait analysis compared to a three-dimensional motion analysis system in healthy dogs.

The goal of this study was to compare the accuracy of kinematic measurements obtained using the 2-D video-based kinematic motion analysis (KMA) software Kinovea (version 0.9.5; http://www.kinovea.org) with 3-D KMA in healthy dogs. In this prospective study, 3-D marker-based KMA (VICON-Nexus, version 2.12.1, and Procalc, version 1.6; VICON Motion Systems Ltd) was performed on healthy dogs (body weight ≥ 20 kg; height at withers > 50 cm) walking on a treadmill (study period: November 2022). Simultaneously, dogs were video recorded by 1 smartphone (iPhone SE; Apple Inc) at a 1.50-m distance perpendicular to the shoulder (60 frames per second; 1,920 X 1,080 pixels) for KMA using Kinovea. Joint angle and joint angle velocity of the shoulder, elbow, carpus, hip, stifle, and tarsus were calculated for 6 synchronized gait cycles. Each gait cycle was divided into 10 increments. The difference between 3-D KMA and Kinovea was assessed for each parameter using robust linear mixed-effects models. 34 dogs were included. The estimated joint angle difference between 3-D KMA and Kinovea was less than 2° for all shoulder and elbow gait cycle increments. For the carpus, hip, stifle, and tarsus, the difference was less than 2° in 9, 5, 4, and 4 out of 10 gait cycle increments, respectively. Kinovea provides accurate kinematic data for the shoulder and elbow of healthy dogs. Carpal, hip, stifle, and tarsal kinematics were less accurate. The use of Kinovea for clinical and research purposes remains limited. Future Kinovea-based studies are needed to investigate the accuracy of carpal, hip, stifle, and tarsal kinematics.

Discursive Strategy in ‘Self-Celebritizing’ Entrepreneurial Firms: Video-Based Analysis of SpaceX

Discursive Strategy in ‘Self-Celebritizing’ Entrepreneurial Firms: Video-Based Analysis of SpaceX

How and why does it work? A video-based qualitative analysis of case conferences to reduce BPSD through the lens of Habermas’s theory of communicative action

BackgroundCase conferences are described as a goal-oriented, systematic method that team members can use to exchange professional opinions and develop treatment actions for a particular care problem. However, not all case conferences have proven to be effective. The Norwegian Targeted Interdisciplinary Model for the Evaluation and Treatment of Neuropsychiatric Symptoms (TIME) is an effective multicomponent model based on case conferences that informs approaches to behavioural and psychological symptoms in residents with dementia in nursing homes. Our aim was to explore how TIME case conferences structured based on cognitive behavioural therapy (CBT) contributed to person-centred actions and how the specific inductive structure of the TIME may have contributed to the effectiveness of the model.MethodsWe used video observation of six case conferences and analysed these videos by performing a thematic cross-case analysis of the transcripts from the videos and by iteratively watching the videos. According to Habermas’s theory of communicative action, we emphasized the case conference content, i.e., what was talked about in the case conferences, and the display of communication between the participants in the case conferences.ResultsOur findings showed that the theoretical principles behind the TIME, including both person-centred care and the inductive structure of CBT, reflected many aspects of Habermas’s theory of communicative actions. In particular, the TIME case conferences emphasized the lifeworld perspective for both residents and staff and contributed to what Habermas labelled communicative rationality as a means to develop shared understanding among staff and create person-centred action.ConclusionsOne causal assumption of how and why the TIME case conferences contributed to the effectiveness of the TIME in reducing BPSD in nursing homes is that the specific inductive structure of the case conferences with the column technique based on the ABC method together with PCC, emphasized the importance of the lifeworld for both the resident and the staff. Even though case conferences have been highlighted as useful, it is not indifferent how these case conferences are structured and conducted.Clinical trial registrationThe trial TIME was registered January 6, 2016, with clinicaltrials.gov (NCT02655003).

‘No One Is Left Behind?’: A Mixed-Methods Case Study of Equity and Inclusion in Physical Education Teacher Education

Equity and inclusion are requisites of high-quality Physical Education (PE). However, there is a substantial gap in understanding PE Teacher Education’s (PETE) effectiveness in preparing Preservice Teachers (PSTs) to implement equity-driven pedagogies. Moreover, focused on individual retrospective gameplay engagement rates (participation time), current research fails to provide a holistic perspective of the practical manifestations of equity and inclusion in PE. This study fills this void with novel insights offered by a mixed-methods case study examining the following: (i) the process-oriented teaching strategies employed by a PST trained to deliver inclusive pedagogies, alongside student voices on lived experiences; and (ii) the outcome-oriented gameplay patterns across two teaching units (Basketball and Volleyball). Participants included one PST and 26 students. Extensive observations and focus groups mapped the applied teaching strategies and student responses. Video-based social network analysis captured equity and inclusion in students’ gameplay patterns, using metrics such as degree prestige. Findings indicate the PETE impact in inducing PSTs’ inclusive manipulation of learning activities and the fostering of inclusive team membership and positive collaboration. SNA metrics evidenced equitable and inclusive gameplay patterns. Despite pedagogical efforts, content-specific factors may influence students’ gameplay inclusion. Hence, a reflection on the multifaceted and non-linear nature of promoting inclusive participation is prompted.

A network model of stress contagion: evidence from the vocational classroom

PurposeOur study focuses on stress contagion in vocational school classes, examining how students’ stress experiences affect their spatial classmates. For this purpose, we apply a novel formal network model that allows us to differentiate between endogenous and exogenous peer effects in the stress contagion process. Using the network model, we investigate effects on students’ stress levels, considering the stress and coping experiences of spatial peers as well as didactic-methodological context factors.MethodsWe test our statistical model using secondary data collected in a study involving 53 students from two classes at a public German vocational training school. The students’ experiences of stress (time pressure, pressure to succeed) and coping strategies (understanding of the subject matter, self-confidence) were captured using the experience sampling method, while classroom characteristics (e.g., teacher instruction, cooperative work) were recorded through video-based analysis of lessons. Utilizing the panel data, we employ maximum likelihood estimation to assess the spatial peer effects model for both classrooms.ResultsAmong other findings, all model specifications revealed significant peer effects for both stress measures, indicating that the higher the stress experience of immediate peers in the classroom, the higher the individual stress experienced by the students. Concerning the considered context factors, we found, for example, that increased cooperative work leads to higher levels of stress experience.ConclusionFrom a substantive perspective, our results underscore the role of peer-to-peer contagion in the vocational classroom and thus suggest a nuanced examination of cooperative practices. From a research methodology perspective, our approach illustrates how various methods (such as experience sampling, video-based classroom observation, and spatial network information) complement and enrich each other, highlighting the added value of our network analytical approach

The Intertwining of Children’s Interests and Micro-Practices at a Science Museum: Case Study of Three Children

Children’s multiple interests intersect with their participation in informal learning practices in dynamic ways. Using a theoretical framework illustrating interest as a multifaceted construct that has different forms and a range of scope and durability, this study investigates how children’s situational interests and individual interests are developed and reinforced and how they support micro-practices (i.e., any small practices, actions, activities, interactions that occur moment-by-moment) and vice versa. From a larger data set collected from one-time family science learning sessions at a museum, three children (aged 6–10) were strategically sampled to foreground an enhanced understanding of how interest and participation in practice mutually constitute each other. Using video-based interaction analysis, our case study of three children illustrates different patterns where micro-practices intersect with different types of interests at the museum. Even in the same environment with the same exhibits, each child from this case study constructed a unique pathway of forming the collection of micro-practices that was constantly interacting with situational interests and individual interests in specific disciplines, topics, exhibits, or any other various targets. For example, when having a strongly existing individual interest in a specific science discipline, one child’s micro-practices were mainly driven by making choices of exhibits that are related to his science interest, while another child did not actively choose exhibits but found her own creative ways to connect her science interest and other new interests. Our study contributes to a more robust conception of interest that highlights the intertwining of multiple, malleable, and moment-by-moment interests and micro-practices in the museum.

Strategic insights into penalty kick execution: A comprehensive analysis of observable behaviors in the German Bundesliga

This study aimed to investigate which observable variables would be able to predict the penalty taker strategy; and to identify the prevalence of the penalty taker strategy in successful penalty kicks. Dataset consists of 220 penalty kicks from the German Bundesliga (2019-2021). Video-based performance analysis of in-match penalty kicks was performed. Chi-squared (χ2) test and logistic regression (enter method) analyses were performed to investigate the relationship between observable behaviors and the penalty-taker strategy. The following behavior: gaze behavior at the ball, no deception, number of steps more than 3, perceived ball speed as powerful shot, run up speed fast, penalty kick shot height at the center or down, kicking technique instep kick, and run up approach frontal was related to the goalkeeper independent strategy (χ2 (177) = 211.049, 96%, p &lt; .001). In successful penalty kicks the independent goalkeeper strategy was more adopted (59.87%). The differentiation between penalty kick patterns provides scientific and practical insights as it enables researchers to identify patterns in the German Bundesliga. Through analysis of the kicker's running pattern, deception actions, gaze behavior, and kicking technique, football practitioners may attempt to determine the kicker's favored approach, and ultimately the penalty kick strategy, so they can inform coaching staff and players.

Analysing the impact of the 50:22 kick law changes in South African rugby tournaments between 2021 and 2022

ABSTRACT Tactical kicking plays a crucial role in rugby union, influencing both attacking and defensive strategies and potentially impacting a team’s overall success. The introduction of the 50:22 law requires defensive teams to reposition players to anticipate and counter kicks, thereby reducing the number of players in their defensive front line. This study investigated the impact of the 50:22 kicking law on kicking profiles by comparing the 2021 and 2022 seasons, as well as examining the success rate of 50:22 kicks during the 2022 season in South African rugby union tournaments. A retrospective research design was employed, utilising video-based performance analysis software (Nacsport Scout Plus) for data collection. The analysis encompassed all general play kicks from 177 matches spanning two seasons and tournaments, amounting to a total of 6,479 kicks. Within this dataset, there were 53 successful 50:22 kicks out of 162 attempts. Key findings revealed an upswing in kicks by scrum halves (2021: 20%, 2022: 26%; p = 0.00) and a concurrent decline in kicks by fullbacks (2021: 21%, 2022: 18%; p = 0.01). Notably, there was a significant increase in the percentage of kicks occurring in the fourth quarter of the match (2021: 20%, 2022: 22%; p = 0.01). Furthermore, the study identified a noteworthy increase in the percentage of kicks following a turnover (2021: 2%, 2022: 3%; p < 0.01). In conclusion, this research contributes valuable insights into how the 50:22 law shapes kicking strategies in South African rugby union, shedding light on the shifts in player roles and temporal patterns of kicking within the context of this specific law.

Video-Based Kinematic Analysis of Movement Quality in a Phase 3 Clinical Trial of Troriluzole in Adults with Spinocerebellar Ataxia: A Post Hoc Analysis.

Traditional methods for assessing movement quality rely on subjective standardized scales and clinical expertise. This limitation creates challenges for assessing patients with spinocerebellar ataxia (SCA), in whom changes in mobility can be subtle and varied. We hypothesized that a machine learning analytic system might complement traditional clinician-rated measures of gait. Our objective was to use a video-based assessment of gait dispersion to compare the effects of troriluzole with placebo on gait quality in adults with SCA. Participants with SCA underwent gait assessment in a phase 3, double-blind, placebo-controlled trial of troriluzole (NCT03701399). Videos were processed through a deep learning pose extraction algorithm, followed by the estimation of a novel gait stability measure, the Pose Dispersion Index, quantifying the frame-by-frame symmetry, balance, and stability during natural and tandem walk tasks. The effects of troriluzole treatment were assessed in mixed linear models, participant-level grouping, and treatment group-by-visit week interaction adjusted for age, sex, baseline modified Functional Scale for the Assessment and Rating of Ataxia (f-SARA), and time since diagnosis. From 218 randomized participants, 67 and 56 participants had interpretable videos of a tandem and natural walk attempt, respectively. At Week 48, individuals assigned to troriluzole exhibited significant (p=0.010) improvement in tandem walk Pose Dispersion Index versus placebo {adjusted interaction coefficient: 0.584 [95% confidence interval (CI) 0.137 to 1.031]}. A similar, nonsignificant trend was observed in the natural walk assessment [coefficient: 1.198 (95% CI-1.067 to 3.462)]. Further, lower baseline Pose Dispersion Index during the natural walk was significantly (p=0.041) associated with a higher risk of subsequent falls [adjusted Poisson coefficient:-0.356 [95% CI-0.697 to-0.014)]. Using this novel approach, troriluzole-treated subjects demonstrated improvement in gait as compared to placebo for the tandem walk. Machine learning applied to video-captured gait parameters can complement clinician-reported motor assessment in adults with SCA. The Pose Dispersion Index may enhance assessment in future research. TRIAL REGISTRATION-CLINICALTRIALS. NCT03701399.

Utilizing data-driven algorithms for blind modal parameter identification of structures from output-only video measurements

In structural dynamics and vibration analysis, modal identification plays a pivotal role in understanding and characterizing the dynamic behavior of complex systems. Traditional modal analysis techniques heavily rely on accurate sensor placement and knowledge of the excitation forces, which may not always be feasible or practical in real-world scenarios. Recently, non-contact video-based modal analysis methods for structures with arbitrary complexity using computer vision techniques have gained much importance. But these methods need to know ahead of time where the structure's natural frequency ranges are, and they use steerable pyramids, which are complicated multi-scale image decomposition filters. To address these issues, a blind modal identification technique is suggested to extract the modal parameters (modal frequency and mode shapes) from the recorded structural vibration video signal. The proposed algorithm for unsupervised machine learning is the Non-Negative Matrix Factorization (NNMF) method, which is combined with the Generalized Complexity Pursuit (GCP) method for blind source separation. The NNMF algorithm is directly applied to the raw pixel-time series made from the video data to get the temporal components, which are then separated using GCP to find the individual modal frequencies and mode shapes. The above algorithm is first validated on a numerical model and then implemented on laboratory scale models (cantilever, single-degree, and multi-degree frame models). Finally, the proposed methodology is implemented on real-world recorded structural vibration videos to determine its noise sensitivity, such as the Tacoma Narrows bridge and the London Millennium footbridge. The modal parameters extracted are compared with those from the available literature for validation. The estimation errors obtained from all the validations are well below 1%, which makes the technique quite suitable and reliable for structural vibration monitoring by identifying and reproducing complex vibration modes.

Injury incidence and associated factors among soccer players during the 2021 African Cup of Nations competition

Background Understanding the epidemiology of soccer injuries during specific international competitions is essential for customizing preventive strategies. Several studies have reported outcomes related to international competitions but, to the best of our knowledge, there has been no investigation into the injury patterns during any African Cup of Nations (AFCON) tournaments. This study aimed to analyse the incidence and the characteristics of soccer injuries during the 2021 African Cup of Nations (AFCON), which took place in Cameroon from January 9 to February 6, 2022. Methods A video-based analysis covering 52 matches was conducted by two independent consultant physicians. They reviewed injury replays to determine incidence and characteristics ( i.e. ; mechanisms, body location, match moment, player substitution, absence in the next match, and referee decisions). Results The tournament involved 519 male players, comprising 275 African (ALP) and 244 Non-African (NALP) league players. Eighty-seven injuries occurred, with incidences of 1.7 and 48.8 injuries per match and per 1000 match hours, respectively. Injury incidence rose with competition stages, particularly contact mechanism injuries. Non-contact injuries (23/87) predominantly occurred after 60 minutes of play (19/23), with the thigh being the most frequently affected body part (18/87). Older age and playing time significantly correlated with injury occurrence (p=0.032 and p&lt;0.001, respectively). NALP midfielders and forwards were notably injured by contact mechanisms (36/45) in the attacking zone. Although non-contact mechanisms were more common in ALP than NALP (13/42 vs. 9/45), the difference lacked statistical significance (p=0.240), with a higher rate of muscle injuries (13/42 vs. 10/45, p=0.001). Conclusion Muscle injuries prevailed among professional soccer players in the 2021 AFCON, with older age and playing time identified as key associated factors. Muscle injuries were more prevalent in ALP compared to NALP.