Mechanical Artifacts Research Articles

Wireless high-resolution surface facial electromyography mask for discrimination of standardized facial expressions in healthy adults

Wired high resolution surface electromyography (sEMG) using gelled electrodes is a standard method for psycho-physiological, neurological and medical research. Despite its widespread use electrode placement is elaborative, time-consuming, and the overall experimental setting is prone to mechanical artifacts and thus offers little flexibility. Wireless and easy-to-apply technologies would facilitate more accessible examination in a realistic setting. To address this, a novel smart skin technology consisting of wireless dry 16-electrodes was tested. The soft electrode arrays were attached to the right hemiface of 37 healthy adult participants (60% female; 20 to 57 years). The participants performed three runs of a standard set of different facial expression exercises. Linear mixed-effects models utilizing the sEMG amplitudes as outcome measure were used to evaluate differences between the facial movement tasks and runs (separately for every task). The smart electrodes showed specific activation patterns for each of the exercises. 82% of the exercises could be differentiated from each other with very high precision when using the average muscle action of all electrodes. The effects were consistent during the 3 runs. Thus, it appears that wireless high-resolution sEMG analysis with smart skin technology successfully discriminates standard facial expressions in research and clinical settings.

When performing actions with robots, attribution of intentionality affects the sense of joint agency.

Sense of joint agency (SoJA) is the sense of control experienced by humans when acting with others to bring about changes in the shared environment. SoJA is proposed to arise from the sensorimotor predictive processes underlying action control and monitoring. Because SoJA is a ubiquitous phenomenon occurring when we perform actions with other humans, it is of great interest and importance to understand whether-and under what conditions-SoJA occurs in collaborative tasks with humanoid robots. In this study, using behavioral measures and neural responses measured by electroencephalography (EEG), we aimed to evaluate whether SoJA occurs in joint action with the humanoid robot iCub and whether its emergence is influenced by the perceived intentionality of the robot. Behavioral results show that participants experienced SoJA with the robot partner when it was presented as an intentional agent but not when it was presented as a mechanical artifact. EEG results show that the mechanism that influences the emergence of SoJA in the condition when the robot is presented as an intentional agent is the ability to form similarly accurate predictions about the sensory consequences of our own and others' actions, leading to similar modulatory activity over sensory processing. Together, our results shed light on the joint sensorimotor processing mechanisms underlying the emergence of SoJA in human-robot interaction and underscore the importance of attribution of intentionality to the robot in human-robot collaboration.

The type 1 submovement conundrum: an investigation into the function of velocity zero-crossings within two-component aiming movements

In rapid manual aiming, traditional wisdom would have it that two components manifest from feedback-based processes, where error accumulated within the primary submovement can be corrected within the secondary submovement courtesy of online sensory feedback. In some aiming contexts, there are more type 1 submovements (overshooting) compared to types 2 and 3 submovements (undershooting), particularly for more rapid movements. These particular submovements have also been attributed to a mechanical artefact involving movement termination and stabilisation. Hence, the goal of our study was to more closely examine the function of type 1 submovements by revisiting some of our previous datasets. We categorised these submovements according to whether the secondary submovement moved the limb closer (functional), or not (non-functional), to the target. Overall, there were both functional and non-functional submovements with a significantly higher proportion for the former. The displacement at the primary and secondary submovements, and negative velocity peak were significantly greater in the functional compared to non-functional. The influence of submovement type on other movement characteristics, including movement time, was somewhat less clear. These findings indicate that the majority of type 1 submovements are related to intended feedforward- and/or feedback-based processes, although there are a portion that can be attributed an indirect manifestation of a mechanical artefact. As a result, we suggest that submovements should be further categorised by their error-reducing function.

Multifocal Atrial Tachycardia Transitioning to Atrial Fibrillation in an Octogenarian

Abstract Multifocal atrial tachycardia (MAT) is an arrhythmia frequently seen in the elderly whose prevalence increases with aging. These arrhythmias may eventually lead to more chaotic arrhythmias such as atrial fibrillation (AF) and flutter. MAT is frequently mistaken for AF in electrocardiogram (ECG). The importance of differentiating MAT from AF is that the former requires no anticoagulation and, therefore, avoids the risks associated with their administration. It is also important to realize that the elderly have multiple conditions such as senile tremors and Parkinson’s disease which may cause mechanical movement artifacts in resting ECGs mimicking cardiac arrhythmias leading to incorrect interpretation of ECGs. Educating physicians about the electrocardiographic appearance of atrial dysrhythmias and the recognition of the confounding artifacts can prevent unnecessary use of treatment which could potentially cause adverse effects in the patient.

Impact of CT-guided hookwire localization on tumor spread through air spaces in stage IA lung adenocarcinoma

BackgroundIt remains undetermined whether preoperative computed tomography (CT)-guided hookwire localization would result in elevated risk of tumor spread through air spaces (STAS) in stage IA lung adenocarcinoma. MethodsA total of 1836 patients who underwent lobectomy were included. To eliminate the potential impact of confounding factors on producing STAS, propensity score–matching (PSM) was used to create two balanced subgroups stratified by implementation of hookwire localization. We also introduced an external cohort including 1486 patients to explore the effect of hookwire localization on the incidence of STAS and patient survival after sublobar resection (SR). For proactive simulation of hookwire localization, 20 consecutive lobectomy specimens of p-stage IA lung adenocarcinoma were selected. ResultsEx vivo tests revealed that mechanical artifacts presenting as spreading through a localizer surface (STALS) could be induced by hookwire localization but be distinguished by CD68 and AE1/3 antibody-based immunohistochemistry. The distance of STALS dissemination tended to be shorter compared with real STAS (P = 0.000). After PSM, implementation of hookwire localization was not associated with elevated STAS incidence, nor worse survival in p-stage IA patients undergoing lobectomy irrespective of STAS. ConclusionsCT-guided hookwire localization might induce mechanical artifacts presenting as STALS which could be distinguished by immunohistochemistry, but would not affect survival in p-stage IA disease. Surgeons can be less apprehensive about performing hookwire localization in relation to STAS on stage IA disease suitable for SR.

Out of Time: Ekphrasis, Narration, and Temporal Experience in Twelfth-Century Romances of Antiquity

This article considers the affective and conceptual work demanded in sophisticated moments of ekphrasis that abound in twelfth-century Old French romances, with particular attention to Alexandre de Paris's Roman d'Alexandre (1180s) and to two of the trio of romans d'antiquité, composed in French at the court of Henry II in England: the Roman de Thebes (c. 1150) and Benoît de Sainte-Maure's Roman de Troie (1165). Of concern is the description of mechanical artefacts or tents that are depicted with representations of temporal progression, in the light of Virgil, Aeneid 8, and Homer, Iliad 18, available to twelfth-century Latins via Baebius's abbreviated Latin epitome. Narrative time stops for these ekphrastic moments which describe the pictorial representation of time. Henri Bergson's concept of duration (durée) and Boethius's representation of human and divine time in Consolation of Philosophy, 4 are used to think through the productive tension between time as forward movement, as represented through narration, and time as juxtaposed stasis, by which events all happen simultaneously, as represented through pictorial representation. Beyond that, the cosmic implications of these temporal questions bring out the relationship between twelfth-century literary ekphrasis and the medieval reception of the cosmogony of Plato's Timaeus. Particular attention is paid to the marvellous tents of Adrastus in the Thebes and of Alexander the Great in the Alexandre; to the chariot of Amphiaraus in the Thebes with its depiction of Ovidian myth and Macrobian cosmos; and to the astonishing cosmogrammatical automaton in the Troie's Chamber of Beauties. Ekphrases of artefacts representing time and the world clearly resonated with medieval audiences; rather than being superfluous to the action, they appear as fundamental to the composition and performance of historical narrative in French romance.

Pressure Pulsatility Links Cardio-Respiratory and Brain Rhythmicity.

This article presents evidence indicating that intracranial pressure (ICP) pulsatility, associated with the heartbeat and breathing, is not just a source of mechanical artefact in electrical recordings, but is "sensed" and plays a role in the brain's information processing. Patch-clamp recording of pressure-activated channels, and detection of Piezo2-protein channel expression in brain neurons, suggest that these channels provide neurons with an intrinsic resonance to ICP pulsatility, which acts to synchronize remote neural networks. Direct measurements in human patients indicate that heartbeat and breathing rhythms generate intracranial forces of tens of millinewtons, exceeding by orders of magnitude the localized forces shown by atomic force microscopy and optical tweezers to activate Piezo channels in isolated neocortical and hippocampal neurons. Additionally, many human touch and proprioceptors, which are also transduced by Piezo channels, show spiking that is phase-locked to heartbeat- and breathing-induced extracranial pressure pulsations. Finally, based on the observation that low-frequency oscillations modulate the phase and amplitude of high-frequency oscillations, body and brain oscillations are proposed to form a single hierarchical system in which the heartbeat is the basic frequency and scaling factor for all other oscillations. Together, these results support the idea that ICP pulsatility may be elemental in modulating the brain's electrical rhythmicity.

Control and evaluation of a humanoid robot with rolling contact joints on its lower body.

In this paper, we introduce a new teen-sized humanoid platform dubbed DRACO 3, custom-built by Apptronik and altered for practical use by the Human Centered Robotics Laboratory at The University of Texas at Austin. The form factor of DRACO 3 is such that it can operate safely in human environments while reaching objects at human heights. To approximate the range of motion of humans, this robot features proximal actuation and mechanical artifacts to provide a high range of hip, knee, and ankle motions. In particular, rolling contact mechanisms on the lower body are incorporated using a proximal actuation principle to provide an extensive vertical pose workspace. To enable DRACO 3 to perform dexterous tasks while dealing with these complex transmissions, we introduce a novel whole-body controller (WBC) incorporating internal constraints to model the rolling motion behavior. In addition, details of our WBC for DRACO 3 are presented with an emphasis on practical points for hardware implementation. We perform a design analysis of DRACO 3, as well as empirical evaluations under the lens of the Centroidal Inertia Isotropy (CII) design metric. Lastly, we experimentally validate our design and controller by testing center of mass (CoM) balancing, one-leg balancing, and stepping-in-place behaviors.

Toward a digital materials mechanical testing lab

To accelerate the growth of Industry 4.0 technologies, the digitalization of mechanical testing laboratories as one of the main data-driven units of materials processing industries is introduced in this paper. The digital lab infrastructure consists of highly detailed and standard-compliant materials testing knowledge graphs for a wide range of mechanical testing processes, as well as some tools that enable the efficient ontology development and conversion of heterogeneous materials’ mechanical testing data to the machine-readable data of uniform and standardized structures. As a basis for designing such a digital lab, the mechanical testing ontology (MTO) was developed based on the ISO 23718 and ISO/IEC 21838-2 standards for the semantic representation of the mechanical testing experiments, quantities, artifacts, and report data. The trial digitalization of materials mechanical testing lab was successfully performed by utilizing the developed tools and knowledge graph of processes for converting the various experimental test data of heterogeneous structures, languages, and formats to standardized Resource Description Framework (RDF) data formats. The concepts of data storage and data sharing in data spaces were also introduced and SPARQL queries were utilized to evaluate how the introduced approach can result in the data retrieval and response to the competency questions. The proposed digital materials mechanical testing lab approach allows the industries to access lots of trustworthy and traceable mechanical testing data of other academic and industrial organizations, and subsequently organize various data-driven research for their faster and cheaper product development leading to a higher performance of products in engineering and ecological aspects.

Live Cell Light Sheet Imaging with Low- and High-Spatial-Coherence Detection Approaches Reveals Spatiotemporal Aspects of Neuronal Signaling

Light sheet microscopy in live cells requires minimal excitation intensity and resolves three-dimensional (3D) information rapidly. Lattice light sheet microscopy (LLSM) works similarly but uses a lattice configuration of Bessel beams to generate a flatter, diffraction-limited z-axis sheet suitable for investigating subcellular compartments, with better tissue penetration. We developed a LLSM method for investigating cellular properties of tissue in situ. Neural structures provide an important target. Neurons are complex 3D structures, and signaling between cells and subcellular structures requires high resolution imaging. We developed an LLSM configuration based on the Janelia Research Campus design or in situ recording that allows simultaneous electrophysiological recording. We give examples of using LLSM to assess synaptic function in situ. In presynapses, evoked Ca2+ entry causes vesicle fusion and neurotransmitter release. We demonstrate the use of LLSM to measure stimulus-evoked localized presynaptic Ca2+ entry and track synaptic vesicle recycling. We also demonstrate the resolution of postsynaptic Ca2+ signaling in single synapses. A challenge in 3D imaging is the need to move the emission objective to maintain focus. We have developed an incoherent holographic lattice light-sheet (IHLLS) technique to replace the LLS tube lens with a dual diffractive lens to obtain 3D images of spatially incoherent light diffracted from an object as incoherent holograms. The 3D structure is reproduced within the scanned volume without moving the emission objective. This eliminates mechanical artifacts and improves temporal resolution. We focus on LLS and IHLLS applications and data obtained in neuroscience and emphasize increases in temporal and spatial resolution using these approaches.

Mechanical and Structural Artefacts Used in “The Mystery of Elche”

In the city of Elche, every year, on the 14th and 15th of August, a sacred musical play about the death, the Assumption and the Coronation of the Virgin Mary is held. This event, known as the “Misterio de Elche”, is unique in the world. Since the middle of the 15th century it has been performed in the Basilica of Santa Maria and in the streets of the ancient city of Elche, located in the Valencian Community. In this work, classified as a UNESCO World Heritage Site, the interior of the temple is transformed into 2 main stages, the scaffold, located in the lower part, and the aerial stage, located in the dome at a height of 27 m. The structure and the traction mechanisms located on the aerial stage allow the aerial devices that take part in the play, “El Araceli”, “La Mangrana” and “La Santísima Trinidad”, to be raised and lowered. It should be noted that between 2 and 5 singing actors are embarked on these devices. This article describes the main characteristics of the aerial stage structure, the 3 apparatus and the mechanical systems used. In addition, the age and modifications of “El Araceli” are analysed, as well as the results of a non-destructive test carried out on this device.

Mechanical artifacts in optical projection tomography: classification and automatic calibration

Optical projection tomography (OPT) is a powerful tool for biomedical studies. It achieves 3D visualization of mesoscopic biological samples with high spatial resolution using conventional tomographic-reconstruction algorithms. However, various artifacts degrade the quality of the reconstructed images due to experimental imperfections in the OPT instruments. While many efforts have been made to characterize and correct for these artifacts, they focus on one specific type of artifacts, whereas a comprehensive catalog of all sorts of mechanical artifacts does not currently exist. In this work, we systematically document many mechanical artifacts. We rely on a 3D description of the imaging system that uses a set of angular and translational parameters. We provide a catalog of artifacts. It lists their cause, resulting effects, and existing correction methods. Then, we introduce an automatic calibration algorithm that is able to recover the unknown system parameters fed into the final 3D iterative reconstruction algorithm for a distortion-free volumetric image. Simulations with beads data and experimental results on a fluorescent textile fiber confirm that our algorithm successfully removes miscalibration artifacts in the reconstruction.

An Analysis of Noise in Multi-Bit ΣΔ Modulators with Low-Frequency Input Signals.

Digital and smart sensors are commonly implemented using multi-bit Modulators. Undesired signals can be present at the ADC input, such as low-frequency signals with medium or high amplitude, as a consequence of mechanical artifacts in the MEMS and/or temporary signal overload. Simulations and measurements of those sensors with such signals show temporary increments of in-band noise power. This paper investigates the factors that produce this transient performance loss. Interestingly, noise increments happen when the modulator is forced to toggle between three adjacent levels and is not correlated with the typical tonal behavior of Modulators. Hence, the sensor performance is sensitive to some specific input patterns even if tonal behavior is decreased by dithering the input of the ADC. Different error sources, such as the mismatch between DAC cells, loop filter linearity error, and quantization error, contribute to the observed noise increments. Our aim is to analyze each of these error sources to understand and quantify in-band noise power increments, and to desensitize the ADC from the undesired input patterns. Some estimation equations are proposed and verified through extensive simulations, by means of deterministic and stochastic methods. These equations are influenced by some modulator parameters and can be used to optimize them in order to reduce such in-band noise power increments.

A simplified design of a cEEGrid ear-electrode adapter for the OpenBCI biosensing platform

We present a simplified design of an ear-centered sensing system built around the OpenBCI Cyton & Daisy biosignal amplifiers and the flex-printed cEEGrid ear-EEG electrodes. This design reduces the number of components that need to be sourced, reduces mechanical artefacts on the recording data through better cable placement, and simplifies the assembly. Besides describing how to replicate and use the system, we highlight promising application scenarios, particularly the observation of large-amplitude activity patterns (e.g., facial muscle activities) and frequency-band neural activity (e.g., alpha and beta band power modulations for mental workload detection). Further, examples for common measurement artefacts and methods for removing them are provided, introducing a prototypical application of adaptive filters to this system. Lastly, as a promising use case, we present findings from a single-user study that highlights the system's capability of detecting jaw clenching events robustly when contrasted with 26 other facial activities. Thereby, the system could, for instance, be used to devise applications that reduce pathological jaw clenching and teeth grinding (bruxism). These findings underline that the system represents a valuable prototyping platform for advancing ear-based electrophysiological sensing systems and a low-cost alternative to current commercial alternatives.

Sibernetik Felsefe, Performatiflik ve Yeni Medya Estetiği

By drawing upon philosophical repercussions of cybernetics, this article reformulates the notion of performativity in the context of new media aesthetics. It links performativity to new media aesthetics via the cybernetic notions of information processing and generating systems, recursive electronic and digital feedback loops, emergency, complexity, dynamism, and autonomously evolving systems. In doing so, I argue that the operational logic and infrastructure of new media technologies can only be understood from a performative perspective. The term performance basically refers here to the movement which governs the generation and transformation of systems by putting them into action. It is through this action that the various components and parts of a system relay and process information and produce complex interactive systems. As a result, this kind of complex interactivity leads to the emergence of new forms. It is in this way that these complex systems produce new codes, configurations, and constellations. Such a formulation constitutes my starting point to describe a hybrid framework that may eventually lead to a better understanding of the essential characteristics of new media technologies and aesthetics. The shift from single, discrete, and isolated mechanical artifacts to technological systems laid the foundations for a new kind of aesthetics, the aesthetics of information processing and generating systems. The study of the art object as a system or an environment rather than a single object is crucial to address the way in which the system itself might be conceived of as an aesthetic medium. I foreground my definition of new media in the notions of medium and mediation and discuss the aesthetic possibilities brought forth by the emergence and advancement of information and communication technologies. The method used in this article is literature review.

Cuticular pad–inspired selective frequency damper for nearly dynamic noise–free bioelectronics

Bioelectronics needs to continuously monitor mechanical and electrophysiological signals for patients. However, the signals always include artifacts by patients' unexpected movement (such as walking and respiration under approximately 30 hertz). The current method to remove them is a signal process that uses a bandpass filter, which may cause signal loss. We present an unconventional bandpass filter material-viscoelastic gelatin-chitosan hydrogel damper, inspired by the viscoelastic cuticular pad in a spider-to remove dynamic mechanical noise artifacts selectively. The hydrogel exhibits frequency-dependent phase transition that results in a rubbery state that damps low-frequency noise and a glassy state that transmits the desired high-frequency signals. It serves as an adaptable passfilter that enables the acquisition of high-quality signals from patients while minimizing signal process for advanced bioelectronics.

Comparative Sample Preparation Using Focused Ion Beam and Ultramicrotomy of Human Dental Enamel and Dentine for Multimicroscopic Imaging at Micro- and Nanoscale.

(1) Background: The aim of this study was to systematically compare TEM sections of mineralized human enamel and dentine prepared by focused ion beam (in situ lift-out) technique and ultramicrotomy through a combination of microscopic examination methods (scanning electron microscopy and transmission electron microscopy). In contrast with published studies, we compared the TEM preparation methods using the same specimen blocks as those for the ultramicrotomy and FIB technique. (2) Methods: A further evaluation of TEM sample preparation was obtained by confocal laser scanning microscopy and atomic force microscopy. In addition, ultramicrotome- and focused ion beam-induced artefacts are illustrated. (3) Results: The FIB technique exposed a major difference between non-decalcified enamel and dentine concerning the ultrastructural morphology compared to ultramicrotome-prepared sections. We found that ultramicrotomy was useful for cutting mineralized dentine, with the possibility of mechanical artefacts, but offers limited options for the preparation of mineralized enamel. FIB preparation produced high-quality TEM sections, showing the anisotropic ultrastructural morphology in detail, with minor structural artefacts. Our results show that the solution of artificial saliva and glutardialdehyde (2.5% by volume) is a very suitable fixative for human mineralized tissue. (4) Conclusions: The protocol that we developed has strong potential for the preparation of mineralized biomaterials for TEM imaging and analysis.

Social robots as depictions of social agents.

Social robots serve people as tutors, caretakers, receptionists, companions, and other social agents. People know that the robots are mechanical artifacts, yet they interact with them as if they were actual agents. How is this possible? The proposal here is that people construe social robots not as social agents per se, but as depictions of social agents. They interpret them much as they interpret ventriloquist dummies, hand puppets, virtual assistants, and other interactive depictions of people and animals. Depictions as a class consist of three physical scenes with part-by-part mappings between them: (a) a base scene (the raw physical artifact), (b) the depiction proper (the artifact construed as a depiction), and (c) the scene depicted (the scene people are to imagine). With social robots, evidence shows people form the same three scenes plus mappings: They perceive the raw machinery of a robot, construe it as a depiction of a character, and, using the depiction as a guide, engage in the pretense that they are interacting with the character depicted. With social robots, people also recognize three classes of agents - the characters depicted, the intended recipients of the depictions (those who view or interact with the robots), and the authorities responsible for the robots (the designers, makers, and owners). Construing social robots as depictions, we argue, accounts for many phenomena not covered by alternative models.

Intercellular nuclear migration in cryofixed tobacco male meiocytes.

In this study, intercellular nuclear migration (INM), also known as cytomixis, was documented in cryofixed plant meiocytes for the first time. Intact tobacco inflorescences and flower buds as well as dissected individual anthers were cryofixed in liquid nitrogen by plunge freezing. Cryosubstituted and cryosectioned male meiocytes were analyzed by light microscopy. For cryosubstitution, the frozen material was kept in acetic alcohol at - 70°C for 1week. For cryosectioning, the frozen material was sectioned at - 20°C, and fixed with precooled acetic alcohol. Fixation of the intact tobacco inflorescences in Carnoy's solution was used as a control. Microscopy revealed good preservation of cell structure in the cryofixed anthers, flower buds, and inflorescences. INM was detectable in all the studied cryofixed and chemically fixed samples. The cytological picture of INM observed in the cryofixed meiocytes did not noticeably differ from the picture obtained with the chemically fixed cells. These results indicate that INM is observable irrespective of whether a physical or chemical fixation method is employed, with minimal damage from handling. Our results contradict the notion that INM is a phenomenon caused by mechanical, osmotic, or chemical artifacts during sample preparation.

Transcutaneous Measurement of Essential Vitamins Using Near-Infrared Fluorescent Single-Walled Carbon Nanotube Sensors.

Vitamins such as riboflavin and ascorbic acid are frequently utilized in a range of biomedical applications as drug delivery targets, fluidic tracers, and pharmaceutical excipients. Sensing these biochemicals in the human body has the potential to significantly advance medical research and clinical applications. In this work, a nanosensor platform consisting of single-walled carbon nanotubes (SWCNTs) with nanoparticle corona phases engineered to allow for the selective molecular recognition of ascorbic acid and riboflavin, is developed. The study provides a methodological framework for the implementation of colloidal SWCNT nanosensors in an intraperitoneal SKH1-E murine model by addressing complications arising from tissue absorption and scattering, mechanical perturbations, as well as sensor diffusion and interactions with the biological environment. Nanosensors are encapsulated in a polyethylene glycol diacrylate hydrogel and a diffusion model is utilized to validate analyte transport and sensor responses to local concentrations at the boundary. Results are found to be reproducible and stable after exposure to 10% mouse serum even after three days of in vivo implantation. A geometrical encoding scheme is used to reference sensor pairs, correcting for in vivo optical and mechanical artifacts, resulting in an order of magnitude improvement of p-value from 0.084 to 0.003 during analyte sensing.