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    Shoulder Kinematic and Muscle Activity Compensations to Scapular Stabilizer Weakness: An Optimal Control Framework
    (Springer Nature, 2026-03-04) Russell, Matthew S.; Mulla, Daanish M.; Keir, Peter J.; Chadwick, Edward K.; Blana, Dimitra; Drake, Janessa D. M.; Chopp-Hurley, Jaclyn N.
    Purpose Shoulder kinematic and muscular redundancy promotes considerable variability, obscuring possible insights into neuromuscular control and compensation mechanisms for muscle weakness or fatigue. The current study harnessed recent advancements in optimal control formulations for computational musculoskeletal models to determine potential neuromuscular control strategies to compensate for isolated muscle weakness. Methods A computational shoulder model characterized by independent clavicular, scapular, and humeral kinematics and 138 muscle elements was used. Optimal control-predicted thoracohumeral elevation kinematics were validated against published empirical kinematics. Force-generating capacity of the upper trapezius, middle trapezius, and lower trapezius, and serratus anterior were individually limited to 75%, 50%, and 25% maximal capacity to generate subsequent optimal control predictions of scapulothoracic kinematic changes associated with muscle weakness. Combined limited maximal force-generating capacity of lower trapezius and serratus anterior was also explored. Results Model-predicted scapulothoracic kinematics showed good agreement with reference data, yet some significant differences were identified below 55° thoracohumeral elevation. Fatigue-mediated kinematic changes were most apparent during sagittal plane elevation. Serratus anterior weakness displayed the largest scapulothoracic kinematic changes at all thresholds of limited force-generating capacity. It also prompted the largest compensatory muscle activity changes from other shoulder muscles, while upper trapezius weakness prompted very little compensatory changes in muscle activity. Conclusion Optimal control simulations were used to identify potential compensation mechanisms for shoulder muscle weakness and predict their effects on scapular kinematics. Findings suggest that thoracohumeral elevation in the scapular plane displayed less trapezius coactivity, both when ‘weakened’ and ‘unweakened.’ Thus, scapular plane tasks may isolate serratus anterior, while frontal plane tasks may achieve more balanced coactivation.
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    Temporary protection in Turkey and Colombia: state interests, entangled migration realities, policy diffusion and the global erosion of refugee protection standards
    (Springer, 2026-05-21) Tolay, Juliette; Gonzalez Siverio, Marcos
    Over the last decade, Turkey and Colombia have emerged as major hosts of displaced populations, responding to the Syrian and Venezuelan displacement crises through the adoption of Temporary Protection (TP) regimes. This article offers an exploratory comparative analysis of the political and policy rationales underpinning their adoption. Analysing both cases in parallel reveals three key insights. First, TP serves state interests by supporting internal and external legitimacy, enabling governments to balance border control, public opinion, and policymaking while managing pressures from the Global North and projecting a positive international image. Second, the study highlights the role of policy diffusion: Colombia’s adoption of TP was indirectly shaped by Turkey’s model, reflecting a broader trend in which the circulation of displacement policies has normalized less protective approaches and has eroded refugee protection standards. Third, both states framed their engagement with displaced populations as rooted in “special” relationships, illustrating how borders intersect with social, cultural, and economic ties. Collectively, these findings challenge conventional understandings of migration policy by foregrounding the political centrality of interconnectedness and by showing how TP functions primarily as tool of state interest for entangled migration states, rather than as a mechanism designed around the needs of displaced communities.
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    Congruency of fatigue-mediated changes in shear wave velocity, upper limb force, muscle activity, and kinematics of the scapular stabilizer muscles
    (Elsevier, 2026-04-09) Russell, Matthew S.; Drake, Janessa D. M.; Chopp-Hurley, Jaclyn N.
    Ultrasonographic shear wave elastography is a new technique for assessing muscle stiffness in vivo. Such insights may be valuable to uncover fatigue-mediated muscle stiffness and control changes at the shoulder, for which much variability remains unexplained through EMG-based methods. This study assessed fatigue-mediated changes in shear wave velocity (SWV), EMG root-mean-squared (RMS) amplitude, EMG mean-power-frequency (MdPF), and force output from upper trapezius, middle trapezius, lower trapezius, and serratus anterior, to determine whether SWV may provide a significant predictive variance in the quantification of muscle fatigue and fatigue-mediated scapulothoracic kinematics changes. 15 males and 15 females had their scapular stabilizer muscles and scapulothoracic kinematics assessed before and after a targeted muscle fatigue protocol. Results indicate that EMG RMS amplitude and EMG MdPF were most sensitive to fatigue-mediated changes at 100% contraction intensity, while SWV appeared most sensitive at 30% and 50% contraction intensity. Scapulothoracic kinematics changes appeared most sensitive to fatigue-mediated EMG MdPF changes. These results suggest that EMG MdPF changes may be elusive in a highly redundant muscular system like the shoulder due to its association with kinematics changes altering load-sharing strategies. SWV increases at contraction intensities ≤ 50% suggest post-exercise muscle edema is a likely physiological mechanism.
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    Robust changepoint detection in the variability of multivariate functional data
    (Taylor and Francis, 2025-05-12) Ramsay, Kelly; Chenouri, Shoja'eddin
    We consider the problem of robustly detecting changepoints in the variability of a sequence of independent multivariate functions. We develop a novel changepoint procedure, called the functional Kruskal–Wallis for covariance changepoint procedure, based on rank statistics and multivariate functional data depth. The functional Kruskal–Wallis for covariance changepoint procedure allows the user to test for at most one changepoint or an epidemic period, or to estimate the number and locations of an unknown number of changepoints in the data. We show that when the ‘signal-to-noise’ ratio is bounded below, the changepoint estimates produced by the functional Kruskal–Wallis for covariance changepoint procedure attain the minimax localisation rate for detecting general changes in distribution in the univariate setting. We also provide the behaviour of the proposed test statistics for the at-most-one-change and epidemic settings under the null hypothesis and, as a simple consequence of our main result, these tests are consistent. In simulation, we show that our method is particularly robust when compared to similar changepoint methods. We present an application of the functional Kruskal–Wallis for covariance changepoint procedure to intraday asset returns and functional magnetic resonance imaging scans. As a by-product of our main result, we provide a concentration result for integrated functional depth functions, which may be of general interest.
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    Optimized Volt/VAR Control for Inverter-Interfaced Distributed Energy Resources in Compliance with IEEE 1547 Standards
    (Institute of Central Computation and Knowledge, 2025-06-05) Shaterabadi, Mohammad
    The increasing integration of distributed energy resources (DERs), such as photovoltaic(PV) systems and battery storage, into distribution networks necessitates advanced inverter controls to maintain stable grid operations. IEEE Standard 1547 permits smart inverter functionalities, including Volt/VAR control, enabling DERs to autonomously manage voltage fluctuations caused by varying load and generation conditions. However, configuring these Volt/VAR settings optimally is challenging, as default parameters provided by standards may not ensure optimal performance or dynamic stability. This paper proposes a customized, per-node Volt/VAR control optimization framework for single-phase distribution feeders, adapting inverter control parameters based on expected short-term load and solar generation patterns. Leveraging a projected gradient descent optimization approach, proposed methodology guarantees dynamic stability by approximating feasible operational parameters within a convex polytope and ensuring full compliance with IEEE 1547 voltage and reactive power specifications. Comprehensive numerical evaluations conducted on the IEEE 141-bus distribution system using realistic operational data demonstrate the effectiveness and practicality of the proposed method, highlighting improved voltage stability and regulation compared to conventional approaches.