Continuous Movement Research Articles

Magnetostratigraphy of the Late Cretaceous to Early Eocene sediments from the Tulsipur section, western Nepal: Tectonic implications for the Indian northern passive margin

The sedimentary strata from the Late Cretaceous to Early Eocene in the Himalayan foothills offer detailed insights into land collision processes. Unfortunately, a comprehensive dating study on these strata has been lacking, limiting our understanding of the collision and splicing history of the Indian and Lhasa plates. To address this question, we conducted a paleomagnetic study on the Late Cretaceous to Early Eocene succession in the Tulsipur area, western Nepal. The paleomagnetic data obtained from a 357 m thick succession were used to establish a new magnetostratigraphic framework for this region. The observed magnetic polarity sequence contains six normal and six reversed polarity zones, spanning the age range of 68–54 Ma (Maastrichtian to Early Eocene). In addition, two major and two stable sediment accumulation rates (SARs) were identified which were likely controlled by tectonics. The rifting and subsidence events caused by continuous northward movement of the Indian plate might have modulated the shifting of distal offshore to tidal flat settings in this region. We document fifteen (Unit I) and seven (Unit II) transgressive-regressive cycles, indicative of passive margin instability influenced by near-field effects of the India-Asian convergence. This new magnetostratigraphic result is expected to serve as a basic age framework in reconstructing the Late Mesozoic and Early Cenozoic tectonic evolution. Furthermore, it will also facilitate reliable cross-regional correlation between lithostratigraphic units across passive margins in the southern Himalaya and similar strata in the Tethyan Himalaya and active continental margins of the southern Tibetan Plateau.

Auditory feedback decreases timing variability for discontinuous and continuous motor tasks in autistic adults.

Autistic individuals demonstrate greater variability and timing error in their motor performance than neurotypical individuals, likely due at least in part to atypical cerebellar characteristics and connectivity. These motor difficulties may differentially affect discrete as opposed to continuous movements in autistic individuals. Augmented auditory feedback has the potential to aid motor timing and variability due to intact auditory-motor pathways in autism and high sensitivity in autistic individuals to auditory stimuli. This experiment investigated whether there were differences in timing accuracy and variability in autistic adults as a function of task (discontinuous vs. continuous movements) and condition (augmented auditory feedback vs. no auditory feedback) in a synchronization-continuation paradigm. Ten autistic young adults aged 17-27 years of age completed the within-subjects study that involved drawing circles at 800 milliseconds intervals on a touch screen. In the discontinuous task, participants traced a series of discrete circles and paused at the top of each circle for at least 60 milliseconds. In the continuous task, participants traced the circles without pausing. Participants traced circles in either a non-auditory condition, or an auditory condition in which they heard a tone each time that they completed a circle drawing. Participants had significantly better timing accuracy on the continuous timing task as opposed to the discontinuous task. Timing consistency was significantly higher for tasks performed with auditory feedback. This research reveals that motor difficulties in autistic individuals affect discrete timing tasks more than continuous tasks, and provides evidence that augmented auditory feedback may be able to mitigate some of the timing variability present in autistic persons' movements. These results provide support for future investigation on the use of music-based therapies involving auditory feedback to address motor dysfunction in autistic individuals.

AcquisitionFocus: Joint Optimization of Acquisition Orientation and Cardiac Volume Reconstruction Using Deep Learning.

In cardiac cine imaging, acquiring high-quality data is challenging and time-consuming due to the artifacts generated by the heart's continuous movement. Volumetric, fully isotropic data acquisition with high temporal resolution is, to date, intractable due to MR physics constraints. To assess whole-heart movement under minimal acquisition time, we propose a deep learning model that reconstructs the volumetric shape of multiple cardiac chambers from a limited number of input slices while simultaneously optimizing the slice acquisition orientation for this task. We mimic the current clinical protocols for cardiac imaging and compare the shape reconstruction quality of standard clinical views and optimized views. In our experiments, we show that the jointly trained model achieves accurate high-resolution multi-chamber shape reconstruction with errors of <13 mm HD95 and Dice scores of >80%, indicating its effectiveness in both simulated cardiac cine MRI and clinical cardiac MRI with a wide range of pathological shape variations.

Indoor view graph: A model to capture route and configurational information

This paper presents a graph model that simultaneously stores route and configurational information about indoor spaces. Existing indoor information models either capture route information to compute shortest paths and to generate route descriptions (i.e., answering how-to-get-to questions), or they store configurational information about objects and places and their spatial relationships to enable spatial querying and inference (i.e., answering where-questions). Consequently, multiple representations of an indoor environment must be stored in information systems to address the various information needs of their users. In this paper, we propose a graph that can capture both configurational and route information in a unified manner. The graph is the dual representation of connected lines of sight, or views. Views can represent continuous movement in an indoor environment, and at the same time, the visible configurational information of each view can be explicitly captured. In this paper, we discuss the conceptual design of the model and an automatic approach to derive the view graph from floorplans. Finally, we demonstrate the capabilities of our model in performing different tasks such as calculating shortest paths, generating route descriptions, and deriving place graphs.

Cognitive style of field dependence-independence modulates the working memory storage of biological motion.

The biological motion refers to the continuous configuration movement of live agents in space. The perceptual processing of biological motion has the specificity of the dissociation between body form and body motion. However, there is limited evidence for whether such specificity continues when holding biological motion in working memory. We explored this question from the perspective of field dependence (FD) and field independence (FI) cognitive styles in the current study. Three categories of biological motion have been developed: intact movement, motion feature, and form feature. We examined the working memory capacity of motion features, form features, intact movements (Experiments 1-3), and the recognition of three categories of biological motion when remembering intact movements (Experiment 4). The results showed that for the motion features, FI individuals had better memory performance when remembering five items and showed greater working memory capacity and recognition compared with FD individuals, whereas the opposite pattern was observed between FI and FD individuals for the form features. The cognitive style could modulate the working memory storage of biological motion when the task becomes demanding, suggesting that body form and body motion are dissociable in working memory. Our study provided additional evidence for the specificity of biological motion processing in working memory, extending the hierarchical neural model. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Equilibrium core modeling of a pebble bed reactor similar to the Xe-100 with SCALE

As the nuclear industry moves towards licensing and constructing advanced reactors, new attention has been focused on the advanced reactor designs that have past operational experience, such as pebble-bed high-temperature gas-cooled reactors (PB-HTGRs). Pebble-bed reactor designs have many advantages, such as their higher operating temperatures and online refueling capabilities. However, high-fidelity computational modeling of pebble-bed reactor designs, from reactor startup to operation at equilibrium, is more challenging compared to conventionally fueled reactors due to the continuous movement of the fuel pebbles through the reactor during operation. In previous work at Oak Ridge National Laboratory (ORNL), the SCALE Leap-In method for Cores at Equilibrium (SLICE) was developed around tools within the SCALE code system. This iterative method can effectively generate pebble-bed reactor zone-wise fuel inventories at equilibrium core operation within a reasonable computational time. The objective of this work was to further verify the ORNL SLICE method and to investigate the impact of considering temperature profiles during the application of the method. The SLICE method was applied to a modular high-temperature gas-cooled reactor design based upon publicly available design specifications of the Xe-100 pebble-bed reactor. Upon comparing the results from the SLICE method to published literature, the differences in the eigenvalue keffective were on the order of several hundred pcm (percent millirho). To investigate one possible cause of these differences, a study looking at the sensitivity of the full-core equilibrium keffective and discharge nuclide inventory to temperature was performed by developing equilibrium cores of two additional temperature profiles. From this temperature study, differences on the order of hundreds of pcm for the full-core equilibrium keffective, and up to 15% difference for the discharge inventories were found. These results indicated the strong dependence on temperature that needs to be considered for future work in equilibrium modeling of PB-HTGRs.

Bubble tracking method based on Kuhn-Munkres algorithm for boiling two-phase flow study

The study of bubble dynamics is important in various engineering applications as it can provide a fundamental understanding of the bubbly flow behavior. This paper presents a novel method for tracking bubble trajectories and classifying bubble behaviors, including formation, extinction, continuous movement, fragmentation, and coalescence. The method is based on the theory of perfect matching in bipartite graphs. By establishing the perfect matching between bubbles identified at adjacent time instants, judging the continuity of bubble motion, and simply calculating the number of bubbles in the neighbor of matching bubbles at adjacent time instants, the method can deal with the challenging situation where the bubble position and volume significantly change between two adjacent time instants. The method is validated in a simulated vertical pipe boiling flow, showing that the tracking accuracy is 100% and classification accuracies for continuous movement, fragmentation, and coalescence events are estimated to be larger than 90% in a wide range of time steps between two adjacent time instants.

Hydration Programmable, Shape Memorable Artificial Muscles for Antagonistic Movements

AbstractShape memory polymers (SMPs) capable of generating various deformations from anisotropic temporary shapes to permanent shapes have been emerging as soft robots. However, traditional SMPs cannot imitate the antagonistic movement of human skeletal muscles due to their modulus limitations in shape programming and recovery process. Herein, hydration programmable shape memory polymer (HP‐SMP)‐based fibers that can undergo reversible actuation by assembling antagonistic pairs are reported, where the shape programming of the antagonist muscle relies on the contraction of agonist muscle. HP‐SMP fibers are composed of tunicate cellulose nanocrystals (TCNCs) reinforced semi‐interpenetrating polymer networks. Leveraging their distinctive structure and hydration programmability, the HP‐SMP fibers exhibit large actuation strain (−60%) and high work capacity (751 J kg−1), allowing for reversible actuation under constant stress. Most significantly, the continuous antagonistic movements of HP‐SMP fibers assembled into artificial limbs are demonstrated to realize humanoid motion. This work provides new possibilities for replicating a series of lifelike human movements through the biomimetic design of antagonistic pairs of artificial muscles, utilizing renewable and sustainable biosourced materials.

Study on Relay Contact Bounce Based on the Adaptive Weight Rotation Template Matching Algorithm

In order to analyze the relay action process from an imaging perspective and further investigate the bounce phenomenon of relay contacts during the contact process, this paper utilizes a high-speed shooting platform to capture images of relay action. In light of the situation where the stationary contact in the image is inclined and continuously changing, a rotation template matching algorithm based on adaptive weight is proposed. The algorithm identifies and obtains the inclination angle of the stationary contact, enabling the study of the relay contact bounce process. By extracting contact bounce distance data from the images, a bounce process curve is plotted. Combined with the analysis of the contact bounce process, the reasons for the bounce are explored. The results indicate that the proposed rotation template matching algorithm can accurately identify stationary contacts and their angles at different angles. By analyzing the contact status and bounce process of the relay contacts in conjunction with the relay structure, parameters such as the bounce time, bounce height, and time required to reach the maximum distance can be calculated. Additionally, the main reason for contact bounce in the relay studied in this paper is the limitation imposed on the continued movement of the stationary contact by the presence of the relay brackets when the kinetic energy of the contact is too high. This phenomenon occurs during the first vibration peak in the vibration process after the moving contact contacts the stationary contact. The research results provide a reference for further studying the relay contact bounce process, optimizing relay structure, and suppressing contact bounce.

Investigation into the optoelectrowetting droplet transport mechanism.

To explore the optoelectronic wetting droplet transport mechanism, a transient numerical model of optoelectrowetting (OEW) under the coupling of flow and electric fields is established. The study investigates the impact of externally applied voltage, dielectric constant of the dielectric layer, and interfacial tension between the two phases on the dynamic behavior of droplets during transport. The proposed model employs an improved Young's equation to calculate the instantaneous voltage and contact angle of the droplet on the dielectric layer. Results indicate that, under the influence of OEW, significant variations in the interface contact angle of droplets occur in bright and dark regions, inducing droplet movement. Moreover, the dynamic behavior of droplet transport is closely associated with various parameters, including externally applied voltage, dielectric layer material, and interfacial tension between the two phases, all of which impact the contact angle and, consequently, the transport process. By summarizing the influence patterns of the three key parameters studied, the optimization of droplet transport performance is achieved. The study employs two-dimensional simulation models to emulate the droplet motion under the influence of the electric field, investigating the OEW droplet transport mechanism. The continuous movement of droplets involves three stages: initial wetting, continuous transport, and reaching a steady position. The findings contribute theoretical support for the efficient design of digital microfluidic devices for OEW droplet movement and the selection of key parameters for droplet manipulation.

Dynamic Interplay: Unveiling the Biosphere-Geosphere Nexus in Carbon Cycling

A model describing the interaction of geological and biosphere processes is proposed. It is based on the postulate of the gravitational effect of the bodies of the solar system on the lithosphere plates' movement through magma flows and deep breathing of the Earth. The continuous movement of the plates consist of orogenic cycles. The cycles include a short-term orogenic periods of relatively fast plates' movement and long-term geosynclinal periods of relatively slow movement. The fast movement is caused by rifting, when magma breaks through the thin shell of the lithosphere and hardens in contact with sea water, forming a new plate. During the orogenic period, oceanic plates collide with the continental margin plate in the subduction zone. The energy of the collisions initiates thermochemical sulfate reduction, in which sedimentary organic matter (OM) is oxidized. The resulting CO2 rises to the surface of the Earth, spreads over the planet, initiating photosynthesis. In the geosynclinal period due to the slow plates' movement the released collision energy is insufficient to initiate thermochemical sulfate reduction.

Elephant Trunk Inspired Multimodal Deformations and Movements of Soft Robotic Arms

AbstractElephant trunks are capable of complex, multimodal deformations, allowing them to perform task‐oriented high‐degree‐of‐freedom (DOF) movements pertinent to the field of soft actuators. Despite recent advances, most soft actuators can only achieve one or two deformation modes, limiting their motion range and applications. Inspired by the elephant trunk musculature, a liquid crystal elastomer (LCE)‐based multi‐fiber design strategy is proposed for soft robotic arms in which a discrete number of artificial muscle fibers can be selectively actuated, achieving multimodal deformations and transitions between modes for continuous movements. Through experiments, finite element analysis (FEA), and a theoretical model, the influence of LCE fiber design on the achievable deformations, movements, and reachability of trunk‐inspired robotic arms is studied. Fiber geometry is parametrically investigated for 2‐fiber robotic arms and the tilting and bending of these arms is characterized. A 3‐fiber robotic arm is additionally studied with a simplified fiber arrangement analogous to that of an actual elephant trunk. The remarkably broad range of deformations and the reachability of the arm are discussed, alongside transitions between deformation modes for functional movements. It is anticipated that this design and actuation strategy will serve as a robust method to realize high‐DOF soft actuators for various engineering applications.

Development of programmed trajectories based on the mobility degrees of manipulation robot with a spherical coordinate system for removing oxide film in the production of commercial magnesium

The object of this study is to robotize the technological operation of removing the oxide film from the surface of a magnesium melt poured into continuously moving molds of a casting conveyor for the production of commercial magnesium. To robotize this technological operation, it is proposed to use a two-armed manipulation robot with a spherical coordinate system, which has six degrees of mobility. Software trajectories have been developed according to the degrees of mobility of the manipulation robot in terms of position, speed, and acceleration to perform the technological operation of removing the oxide film from the surface of the magnesium melt poured into the moving molds of the foundry conveyor. Programmed trajectories are described by quadratic polynomials that satisfy restrictions on the values of the generalized coordinate, velocity, and acceleration. These limitations are determined by the design features and energy capabilities of the degrees of mobility drives of the manipulation robot. Programmed trajectories along the first and second degrees of freedom compensate for the continuous movement of the molds of the foundry conveyor. Programmed trajectories along the third and fourth degrees of mobility enable the collection of the oxide film from the surface of the magnesium melt. Programmed trajectories along the fifth and sixth degrees of freedom enable the discharge of the collected oxide film into a special container. The reliability of the developed programmed trajectories is confirmed by the simulation results using MATLAB version R2015b. Based on the results, a cyclogram for controlling a manipulation robot has been constructed to perform the technological operation of removing the oxide film in the production of commercial magnesium. The results could be used in the robotization of technological processes for removing the oxide film in the production of commercial magnesium or similar foundries

Rehabilitation Techniques Before and After Total Knee Arthroplasty for a Better Quality of Life.

The most important gold standard treatment following advanced knee osteoarthritis is total knee arthroplasty. Following surgery oftotal knee replacement, the majority of patients reportdecreased pain and successful long-term results, but recovery is unpredictable, and most patients continue to exhibit muscle weakness in their lower limbs and functional limitations in comparison to similarly aged control individuals. The goal of this review article was to systematically review different articles containing controlled and randomized studies to find out the effectiveness of outpatient care postoperatively on short- and long-term functional recovery. The purpose of this review article is to investigate the possible advantages of pre- and postoperative rehabilitation as well as the value of exercise regimen recommendations following total knee replacement. The following interventions after total knee arthroplasty are discussed in this review article: preoperative education and exercises, continuous passive movement, strengthening interventions, aquatic therapy, balanced training, tourniquet exposure, use of alignment and implants, role of apps in phonesand different wearable devices, influence of postoperative protocols, knee bracing, neuromuscular electrical stimulation, and clinical environment.Strengthening and intense functional exercises for patients above 45 years of age,in landor water programs like aquatic activities, with the increasing intensity of the exercisesin accordance with the patient's progress, should be included in the best outpatient physical therapy protocols. Because these exercises are so precisely personalized, the best long-term effects after surgery may come from outpatient physiotherapy performed in a clinical setting under the supervision of a registered physiotherapist or medical professional. This review article also includes the change in the quality and well-being of a patient's lifewho has undergone total knee arthroplasty and practiced the rehabilitation techniques.

Eye-hand coordination all the way: from discrete to continuous hand movements.

The differentiation between continuous and discrete actions is key for behavioral neuroscience. Although many studies have characterized eye-hand coordination during discrete (e.g., reaching) and continuous (e.g., pursuit tracking) actions, all these studies were conducted separately, using different setups and participants. In addition, how eye-hand coordination might operate at the frontier between discrete and continuous movements remains unexplored. Here we filled these gaps by means of a task that could elicit different movement dynamics. Twenty-eight participants were asked to simultaneously track with their eyes and a joystick a visual target that followed an unpredictable trajectory and whose position was updated at different rates (from 1.5 to 240 Hz). This procedure allowed us to examine actions ranging from discrete point-to-point movements (low refresh rate) to continuous pursuit (high refresh rate). For comparison, we also tested a manual tracking condition with the eyes fixed and a pure eye tracking condition (hand fixed). The results showed an abrupt transition between discrete and continuous hand movements around 3 Hz contrasting with a smooth trade-off between fixations and smooth pursuit. Nevertheless, hand and eye tracking accuracy remained strongly correlated, with each of these depending on whether the other effector was recruited. Moreover, gaze-cursor distance and lag were smaller when eye and hand performed the task conjointly than separately. Altogether, despite some dissimilarities in eye and hand dynamics when transitioning between discrete and continuous movements, our results emphasize that eye-hand coordination continues to smoothly operate and support the notion of synergies across eye movement types.NEW & NOTEWORTHY The differentiation between continuous and discrete actions is key for behavioral neuroscience. By using a visuomotor task in which we manipulate the target refresh rate to trigger different movement dynamics, we explored eye-hand coordination all the way from discrete to continuous actions. Despite abrupt changes in hand dynamics, eye-hand coordination continues to operate via a gradual trade-off between fixations and smooth pursuit, an observation confirming the notion of synergies across eye movement types.

The Effect of Ethical Behavior Strategy on Job Voice, Work Ethics as an Interactive Variable: An Applied Study in the Basra South Oil Company

Ethical behavior and work ethics are among the topics that have received great attention in recent years because of their clear impact on business organizations, as these organizations have begun to work in a continuous movement to issue regulations and ethical codes to form and formulate their goals and principles in a way that frames the ethical responsibility of the organization as well as the extent of their impact on voice performance. career of these organizations After the financial and profit aspect was the goal of business organizations, today they focus on ethical aspects. Rather, organizations seek to outperform competitors by using ethical standards and principles as a criterion for competition. They also determined their impact on the performance of the job voice of employees and the extent to which these standards are reflected in their individual and collective decisions and principles. Therefore, the importance of the study aims to diagnose the extent of the impact of ethical behavior on job performance through work ethics in the South Oil Company / Basra. The study is an applied study in the South Oil Company / Basra. The descriptive analytical statistical approach was adopted, and a questionnaire was prepared and distributed with the aim of testing the study hypotheses. Several questionnaires were distributed to the sample, and a strong direct relationship was found between the variables of the study. One of the most important conclusions reached by the study is that ethical behavior greatly affects job performance, organizational atmosphere, improving relations between employees and senior management, and enhancing trust through adopting work ethics and effective behaviors.

PROCEDURES TO IMPROVE THE EXPORT/IMPORT PROCESS OF OLIVE OILS TO THE BRAZILIAN MARKET

Brazil ranks second among non-producing countries or countries that have lower production compared to consumption. Currently imports of this product reach about 110 thousand tons (2020 data from the Brazilian Ministry of Economy ex-Development and Foreign Trade-MDIC), however, despite the potential for growth in imports and consequently consumption of this product, the entry of this product in national territory has its obstacles and. It is necessary to find improvements in the process and a greater understanding of the entire system so that the import logistics are more effective and beneficial to everyone involved in this activity. The objective of this study was to deal with the main problems related to this procedure(export/import) proposing some solutions for both importers or of oils with practices that optimize this process by streamlining some procedures from the product's exit to the issuance of documentation abroad in accordance with external and internal legal requirements, as well as the continuous movement of the product at the points of arrival in brazilian territory. It is necessary to find improvements in the goods internment process and a greater understanding of the entire legal system so that the import logistics is more effective and benefits everyone involved in this operation. This what the present study proposes to improve this entire process.

Дослідження безпечності перехрестя з круговим рухом

Roads ensure continuous, safe and convenient movement of vehicles. Intersections play a critical role in the road network in terms of capacity, service level and safety. They are designed in different sizes for different purposes and conditions and have their own defining characteristics that can affect their safety and ease of use.&#x0D; Particular attention is paid to roundabouts - where traffic slows down and becomes a one-way flow around a central island. Additional entrance and roundabout lanes improve transportation efficiency, but they also have an impact on safety. The safety disadvantage can be due to inappropriate driver behavior when approaching, circling, and exiting the intersection, as well as weaving maneuvers within the roundabout.&#x0D; The concept of turbo-roundabouts has emerged as a possible alternative to conventional multi-lane intersections, but the analysis of studies does not allow us to draw definitive conclusions about their effectiveness and safety, so it is recommended that such studies be conducted for specific road conditions.&#x0D; The paper proposes a design of a turbo-roundabouts to improve safety without reducing its efficiency at the intersection of international highways (European route E40 «Kyiv–Chop» and E85 «Domanove-Kovel-Chernivtsi-Terebleche») near the city of Dubno, where traffic accidents regularly occur.&#x0D; Among the different types of turbo-roundabouts, the basic turbo-roundabouts with a maximum capacity of up to 2,500 vehicles per hour and the largest traffic flow is taken as a basis.&#x0D; All geometric parameters correspond to the average size of a turbo intersection, take into account the overall dimensions of the truck, the speed of traffic and are built in accordance with the recommendations of regulatory documents of European countries specializing in their design.&#x0D; The designed turbo intersection with circular traffic has the best comparative option and will reduce the overall accident rate by 36 % and the number of injured people by 34 %.

Glutamine Accelerates Post-Exercise Recovery of Arms Power, Leg Power, and Smash Velocity at 48 Hours for Non-Elite Badminton Athletes

Badminton is a sport that is characterized by long-lasting muscle contractions in continuous smash movements which lead to fatigue and glutamine can potentially reduce the incidence of muscle fatigue. The aim of the study is to investigate glutamine affecting post-exercise recovery in non-elite badminton athletes. It was a randomized group pre-test and post-test design. Twenty male students were involved and divided into 2 groups: The placebo (Plac) group was only given instruction for jumping smash activities and mineral water, while the glutamine (Glut) group was jumping smash activities and mineral water containing glutamine. The jumping smash activities were carried out in 10 sets with 20 repetitions with a rest period of 30 seconds per set. Glutamine was given 3 times after 1 hour of jumping smash activities, 24 hours, and 48 hours with a dose of 0.4 grams/KgBW. There were significant differences in the vertical jump, leg power, arm power, and smash velocity in pre-post-2 between the Placebo and Glutamine groups with p&lt;0.05. Meanwhile, no difference was observed in the vertical jump, leg power, arm power, and smash velocity (p&gt;0.05) between the Placebo and Glutamine groups 72 hours after the jumping smash activities (post 3). The administration of glutamine at a dose of 0.4 gram/Kg BW given three times post-jumping smash (eccentric) exercise can accelerate the 48-hour post-exercise recovery of vertical jump, arm power, leg power, and smash velocity. Badminton athletes who play matches daily are expected to consume glutamine to speed up recovery. Keywords: Glutamine; physical exercise; badminton; non-elite athletes

Adaptive changes in BMAL2 with increased locomotion associated with the evolution of unihemispheric slow-wave sleep in mammals.

Marine mammals, especially cetaceans, have evolved a very special form of sleep characterized by unihemispheric slow-wave sleep (USWS) and a negligible amount or complete absence of rapid-eye-movement sleep; however, the underlying genetic mechanisms remain unclear. Here, we detected unique, significant selection signatures in basic helix-loop-helix ARNT like 2 (BMAL2; also called ARNTL2), a key circadian regulator, in marine mammal lineages, and identified two nonsynonymous amino acid substitutions (K204E and K346Q) in the important PER-ARNT-SIM domain of cetacean BMAL2 via sequence comparison with other mammals. In vitro assays revealed that these cetacean-specific mutations specifically enhanced the response to E-box-like enhancer and consequently promoted the transcriptional activation of PER2, which is closely linked to sleep regulation. The increased PER2 expression, which was further confirmed both in vitro and in vivo, is beneficial for allowing cetaceans to maintain continuous movement and alertness during sleep. Concordantly, the locomotor activities of zebrafish overexpressing the cetacean-specific mutant bmal2 were significantly higher than the zebrafish overexpressing the wild-type gene. Subsequently, transcriptome analyses revealed that cetacean-specific mutations caused the upregulation of arousal-related genes and the downregulation of several sleep-promoting genes, which is consistent with the need to maintain hemispheric arousal during USWS. Our findings suggest a potential close relationship between adaptive changes in BMAL2 and the remarkable adaptation of USWS and may provide novel insights into the genetic basis of the evolution of animal sleep.