This paper is focused on tracking control for a rigid body payload, that is connected to an arbitrary number of quadrotor unmanned aerial vehicles via rigid links. An intrinsic form of the equations ...of motion is derived on the nonlinear configuration manifold, and a geometric controller is constructed such that the payload asymptotically follows a given desired trajectory for its position and attitude. The unique feature is that the coupled dynamics between the rigid body payload, links, and quadrotors are explicitly incorporated into control system design and stability analysis. These are developed in a coordinate-free fashion to avoid singularities and complexities that are associated with local parameterizations. The desirable features of the proposed control system are illustrated by a numerical example.
This study considers how governments use state-sponsored propaganda and state violence in tandem to repress social movements and, in so doing, exacerbate polarization. We specifically focus on cases ...in young and non-democracies in East and Southeast Asia: China and Hong Kong, the Free Papua Movement in Indonesia, and Myanmar’s more recent coup. Using a time series analysis, our analysis reveals a temporal relationship between state propaganda and violence; however, we do not find much evidence that these state actions Granger-cause social movement activities. The exception to this is in Myanmar, where we find that repressive state actions decrease activity in Facebook groups criticizing the Tatmadaw, which in turn increases offline protest activities.
Consumer sleep trackers (CSTs) have gained significant popularity because they enable individuals to conveniently monitor and analyze their sleep. However, limited studies have comprehensively ...validated the performance of widely used CSTs. Our study therefore investigated popular CSTs based on various biosignals and algorithms by assessing the agreement with polysomnography.
This study aimed to validate the accuracy of various types of CSTs through a comparison with in-lab polysomnography. Additionally, by including widely used CSTs and conducting a multicenter study with a large sample size, this study seeks to provide comprehensive insights into the performance and applicability of these CSTs for sleep monitoring in a hospital environment.
The study analyzed 11 commercially available CSTs, including 5 wearables (Google Pixel Watch, Galaxy Watch 5, Fitbit Sense 2, Apple Watch 8, and Oura Ring 3), 3 nearables (Withings Sleep Tracking Mat, Google Nest Hub 2, and Amazon Halo Rise), and 3 airables (SleepRoutine, SleepScore, and Pillow). The 11 CSTs were divided into 2 groups, ensuring maximum inclusion while avoiding interference between the CSTs within each group. Each group (comprising 8 CSTs) was also compared via polysomnography.
The study enrolled 75 participants from a tertiary hospital and a primary sleep-specialized clinic in Korea. Across the 2 centers, we collected a total of 3890 hours of sleep sessions based on 11 CSTs, along with 543 hours of polysomnography recordings. Each CST sleep recording covered an average of 353 hours. We analyzed a total of 349,114 epochs from the 11 CSTs compared with polysomnography, where epoch-by-epoch agreement in sleep stage classification showed substantial performance variation. More specifically, the highest macro F1 score was 0.69, while the lowest macro F1 score was 0.26. Various sleep trackers exhibited diverse performances across sleep stages, with SleepRoutine excelling in the wake and rapid eye movement stages, and wearables like Google Pixel Watch and Fitbit Sense 2 showing superiority in the deep stage. There was a distinct trend in sleep measure estimation according to the type of device. Wearables showed high proportional bias in sleep efficiency, while nearables exhibited high proportional bias in sleep latency. Subgroup analyses of sleep trackers revealed variations in macro F1 scores based on factors, such as BMI, sleep efficiency, and apnea-hypopnea index, while the differences between male and female subgroups were minimal.
Our study showed that among the 11 CSTs examined, specific CSTs showed substantial agreement with polysomnography, indicating their potential application in sleep monitoring, while other CSTs were partially consistent with polysomnography. This study offers insights into the strengths of CSTs within the 3 different classes for individuals interested in wellness who wish to understand and proactively manage their own sleep.
We used a set of approximately 200 Arabidopsis thaliana (L.) Heynh. genes that are involved in the control of flowering time as a reference to identify orthologous (or homologous) counterparts of ...these genes in three legume species, that is, Lotus corniculatus L. var. japonicus Regel syn. Lotus japonicus (Regel) K. Larsen, Medicago truncatula Gaertn. (barrel medic), and soybean Glycine max (L.) Merr.. A total of 96, 98, and 304 homologs of flowering genes were identified in L. corniculatus var. japonicus, M. truncatula, and G. max, respectively. Most of these genes were categorized into seven different flowering pathways, including photoperiod, vernalization, gibberellins, autonomous pathways, floral pathway integrators (FPIs), and floral meristem identity. Many key genes, including the FPI genes FT, SOC1, and LFY, are conserved in the legumes while CO, FRI, FLC, and FD were not. Eighteen genes were conserved as single copy genes in all three legume species, including GI, VRN2, COP1, and TSF. The chromosomal distribution of paralog‐rich genes revealed differences in the major evolutionary processes affecting flowering genes in legumes, including whole genome duplication in soybean, tandem duplication in M. truncatula, and ectopic duplication in L. corniculatus var. japonicus. High divergence was observed among the members of large gene families, most containing transcription factors, indicating the accumulation of gene copies and gene divergence during evolutionary adaptations to environmental changes.
This paper presents an iterative formulation to compute the central moments of the matrix Fisher distribution on the three dimensional special orthogonal group up to an arbitrary order.
This paper provides new results for the tracking control of a quadrotor unmanned aerial vehicle (UAV). The UAV has four input degrees of freedom, namely the magnitudes of the four rotor thrusts, that ...are used to control the six translational and rotational degrees of freedom, and to achieve asymptotic tracking of four outputs, namely, three position variables for the vehicle center of mass and the direction of one vehicle body-fixed axis. A globally defined model of the quadrotor UAV rigid body dynamics is introduced as a basis for the analysis. A nonlinear tracking controller is developed on the special Euclidean group SE(3) and it is shown to have desirable closed loop properties that are almost global. Several numerical examples, including an example in which the quadrotor recovers from being initially upside down, illustrate the versatility of the controller.
The attitude of a rigid body evolves on the three-dimensional (3-D) special orthogonal group, and it is often estimated by measuring reference directions, such as gravity or magnetic field, using ...onboard sensors. As a single direction measurement provides a 2-D constraint, it has been widely accepted that at least two nonparallel reference directions should be measured, or the reference direction should change over time, to determine the attitude completely. This article uncovers an intriguing fact that the attitude can actually be estimated by using multiple measurements of a single, fixed reference direction, provided that the angular velocity and the direction measurements are resolved in appropriate frames, respectively. More specifically, after recognizing that the attitude uncertainties propagated over the left-trivialized stochastic kinematics are distinct from those over the right-trivialized one, stochastic attitude observability with single direction measurements is formulated by an information theoretic analysis. These are illustrated by experiments.
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