Activated Platelets Harbour SARS-CoV-2 During Severe COVID-19

Clinical SARS-CoV-2 infection (COVID-19) is characterised by a hyperinflammatory and procoagulant state that increases the risk of thrombosis and death. Despite thromboprophylaxis at least at the conventional doses, incidence as high as 31% has been reported for thrombotic complications in Intensive Care Unit (ICU) patients with COVID-19 infections. Still, it remains unclear how SARS-Cov-2 may initiate and or perpetuates the intractable thrombo-inflammatory states in COVID-19; and the need to understand the underlying mechanisms is urgent. In this image report, we utilised a state-of-the-art high-resolution 3D imaging approach to examine the interactions of SARS-CoV-2 with platelets, erythrocytes and leucocytes in blood samples obtained from COVID-19 patients in our ICU; and we visualised platelet procoagulant activity and the spatial localisation of SARS-CoV-2 in platelet-rich-plasma reconstituted to contain erythrocytes and leucocytes. Strikingly, we observed that activated platelets harboured SARS-Cov-2 during severe COVID-19 in our patient that eventually succumbed to the infection. SARS-Cov-2 internalisation into the cytosol was probably via a passive mechanism, as we have previously established that actin cytoskeleton remodelling and increased membrane permeability occurred during platelet transformation to the procoagulant phenotype. More work is needed to understand platelets’ role in the recalcitrant thrombotic states of COVID-19.

Model-Based Design and Optimization of Passive Shoulder Exoskeletons

To physically assist workers in reducing musculoskeletal strain or to develop motor skills for patients with neuromuscular disabilities, recent research has focused on Exoskeletons (Exos). Designing active Exos is challenging due to the complex human geometric structure, the human-Exoskeleton wrench interaction, the kinematic constraints, and the selection of power source characteristics. Because of the portable advantages of passive Exos, designing a passive shoulder mechanism has been studied here. The study concentrates on modeling a 3D multibody upper-limb human-Exoskeleton, developing a procedure of analyzing optimal assistive torque profiles, and optimizing the passive mechanism features for desired tasks. The optimization objective is minimizing the human joint torques. For simulating the complex closed-loop multibody dynamics, differential-algebraic equations (DAE)s of motion have been generated and solved. Three different tasks have been considered, which are common in industrial environments: object manipulation, over-head work, and static pointing. The resulting assistive Exoskeleton’s elevation joint torque profile could decrease the specific task’s human shoulder torque. Since the passive mechanism produces a specific torque for a given elevation angle, the Exoskeleton is not versatile or optimal for different dynamic tasks. We concluded that designing a passive Exoskeleton for a wide range of dynamic applications is impossible. We hypothesize that augmenting an actuator to the mechanism can provide the necessary adjustment torque and versatility for multiple tasks.

PASSIVE ATMOSPHERIC WATER HARVESTING UTILIZING AN ANCIENT CHINESE INK SLAB

Extraction of atmospheric water using a passive mechanism instead of a complex and advanced equipment has become an emerging subject. There is a clear record in MengxiBitan by Shen Kuo(1031~1095) that an ink slab has the ability to collect water from the air. Its mechanism is exactly similar to the Fangzhu [1], a recently investigated device for atmospheric water harvesting (AWH). Based on the Fangzhu device, a mathematical model for the AWH mechanism in ink slab-like materials is suggested. Using He’s frequency formulation and two-scale fractal derivatives the possible working mechanism of ink slab-like materials is investigated. The potential applications of ink slab-like structures for AWH in interior and exterior architecture are also presented and discussed. It is revealed that efficiency of the slabs highly depends on velocity and temperature of the flowing air and also its low-frequency characteristics.

The Depth to Magnetic Sources in the Arctic and Its Relationship with Some Parameters of the Lithosphere

––The depth to magnetic sources in twenty Arctic tectonic provinces is determined from azimuthally averaged Fourier power spectra of geomagnetic anomalies according to the EMAG2v3 and WDMAM 2.0 global models. The resulting depths to the centroid and bottom of the magnetic lithosphere are more reliable than the depth to the upper magnetic boundary. The depth to the bottom of magnetic sources, corresponding to the Curie point depth, varies from 25.3 to 38.1 km in different provinces. The Curie point depth estimates are correlated with several parameters of the lithosphere. They are directly proportional to the lithospheric thickness and inversely proportional to average upper mantle temperatures, but the relationship with the intensity of long-wavelength satellite magnetic anomalies and crustal thickness is poor. The magnetic sources are located at crustal depths in most of the provinces, but the upper mantle may be magnetic beneath deep-water oceanic basins and the Laptev Sea. The results for the Laptev Sea shelf support a passive mechanism of current lithospheric extension in the area.

Vision- based control of a mobile manipulator with an adaptable-passive suspension for unstructured environments

The kinematic design and navigation control of a new autonomous mobile manipulator for uneven terrain is presented in this work. An innovative suspension system's design is based on the kinematic synthesis of an adaptable, passive mechanism that compensates for irregularities in the terrain and facilitate the control of the robotic platform using cameras. The proposed mobile robot suspension consists of two pairs of bogies joined by a crank-slider mechanism that allows the robot to adapt to the terrain irregularities. The mobile robot is also equipped with a robotic manipulator, of which a synthesis, simulation, and experimental validation are presented while manipulation is accomplished during movements on rough terrain. The proposed mobile robot has been fabricated using additive manufacturing (AM) techniques. A linear camera space manipulation (LCSM) control system has been developed and implemented to conduct experimental tests along uneven terrain. This mobile manipulator has been designed to transverse uneven terrain so that the loading platform is kept horizontal while crossing obstacles up to one-third of the size of its wheels. This feature allows the onboard cameras to stay oriented towards the target. The vision-based paradigm that enables the control of this mobile manipulator allows to estimate the position and orientation of its end effector and update the trajectory of the manipulator along the path towards the target. The experiments show a final precision for engagement of a pallet within +/− 2.5 mm in position and +/− 2 degrees in orientation.

Singularity Loci, Bifurcated Evolution Routes, and Configuration Transitions of Reconfigurable Legged Mobile Lander from Adjusting, Landing, to Roving

This paper presents the reconfigurable legged mobile lander (ReLML) with its modes from adjusting, landing, to roving. Based on the invented metamorphic variable-axis revolute hinge, the actuated link has three alternative phases of rotating around either of two orthogonal topological axes or locking itself to the base as a rigid body. This property enables the ReLML to switch among three modes and within two driving states (as the adjusting and roving modes are active mechanisms driven by motors, while the landing truss is regarded as a passive mechanism driven by the touchdown impact force exerted on footpad). The unified differential kinematics for the ReLML is established by the screw-based Jacobian modeling, unifying both active and passive operation phases throughout all modes. Afterward, the distributions of workspaces and singularity loci in three modes are discussed for the multi-solution sake, and the selection principle of the practicable solution pattern is proposed to obtain the actual workspace, singularity loci, and configurations. The results stemming from the Jacobian-matrix-based method and the Grassmann-geometry-based method give mutual authentication and match well. Finally, as prospects for promising applications, four bifurcated evolution routes and configuration transitions are figured out and compared.

Dragondrop: a novel passive mechanism for aerial righting in the dragonfly

Dragonflies perform dramatic aerial manoeuvres when chasing targets but glide for periods during cruising flights. This makes dragonflies a great system to explore the role of passive stabilizing mechanisms that do not compromise manoeuvrability. We challenged dragonflies by dropping them from selected inverted attitudes and collected 6-degrees-of-freedom aerial recovery kinematics via custom motion capture techniques. From these kinematic data, we performed rigid-body inverse dynamics to reconstruct the forces and torques involved in righting behaviour. We found that inverted dragonflies typically recover themselves with the shortest rotation from the initial body inclination. Additionally, they exhibited a strong tendency to pitch-up with their head leading out of the manoeuvre, despite the lower moment of inertia in the roll axis. Surprisingly, anaesthetized dragonflies could also complete aerial righting reliably. Such passive righting disappeared in recently dead dragonflies but could be partially recovered by waxing their wings to the anaesthetised posture. Our kinematics data, inverse dynamics model and wind-tunnel experiments suggest that the dragonfly's long abdomen and wing posture generate a rotational tendency and passive attitude recovery mechanism during falling. This work demonstrates an aerodynamically stable body configuration in a flying insect and raises new questions in sensorimotor control for small flying systems.

Threshold of octave masking as a tool to explain cochlear nonlinearity

Background and Aim: The threshold of octave masking test has been used to assess the growth rate of aural harmonics, the intercept point helped differentiate between normal-hearing individuals and sensorineural hearing loss due to noise exposure. With fewer literatures that have been documented, there is a need to explore this test procedure, and hence the purpose of this research is to evaluate the utility of the threshold of octave masking (TOM) procedure in understanding the frequency selectivity and non-linear function of cochlea. Methods: A total of 10 adults (20 ears) were considered for the test. The TOM test procedure was performed on the subjects where the subjects had to identify the presence of a maskee tone (1 kHz) in the presence of a masker tone (500 Hz) across 5 dB increment of masker tone until the subjects uncomfortable level. A line graph was drawn, extrapolated to identify the point of intercept, which is the threshold of octave masking. Results: Results reveal that 17 ears did not have a linear growth but had a 10 to 20 dB gap after a particular maskee level. The intercept point of the initial two extreme points was relatively more than the intercept point of the extreme points at higher intensities. Conclusion: Results from the present study have thrown light on the fact that TOM can be used as a test to measure the frequency selectivity along with the tests of psychophysical tuning curves, notched noise method, non-simultaneous masking, and other non-peripheral masking phenomena. Keywords: Threshold of octave masking; active mechanism; passive mechanism; nonlinearity;frequency selectivity; psychophysical tuning curves