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Animal-borne tags (biologgers) have now become extremely sophisticated, recording data from multiple sensors at high frequencies for long periods and, as such, have become a powerful tool for behavioural ecologists and physiologists studying wild animals. But the design and implementation of these tags is not trivial because engineers have to maximize performance and ability to function under onerous conditions while minimizing tag mass and volume (footprint) to maximize the wellbeing of the animal carriers. We present some of the major issues faced by tag engineers and show how tag designers must accept compromises while maintaining systems that can answer the questions being posed. We also argue that basic understanding of engineering issues in tag design by biologists will help feedback to engineers to better tag construction but also reduce the likelihood that tag-deploying biologists will misunderstand their own results. Finally, we suggest that proper consideration of conventional technology together with new approaches will lead to further step changes in our understanding of wild-animal biology using smart tags. This article is part of the theme issue 'Measuring physiology in free-living animals (Part II)'.

Heart rate monitoring in free-ranging cetaceans to understand their behavioural ecology and diving physiology is challenging. Here, we developed a simple, non-invasive method to monitor the heart rate of cetaceans in the field using an electrocardiogram-measuring device and a single suction cup equipped with an electrode. The unipolar suction cup was placed on the left lateral body surface behind the pectoral fin of Risso's dolphins ( Grampus griseus ) and a false killer whale ( Pseudorca crassidens ) in captivity; their heart rate was successfully monitored. We observed large heart rate oscillations corresponding to respiration in the motionless whales during surfacing (a false killer whale, mean 47 bpm, range 20-75 bpm; Risso's dolphins, mean ± s.d. 61 ± 15 bpm, range 28-120 bpm, n = 4 individuals), which was consistent with the sinus arrhythmia pattern (eupneic tachycardia and apneic bradycardia) observed in other cetaceans. Immediately after respiration, the heart rate rapidly increased to approximately twice that observed prior to the breath. Heart rate then gradually decreased at around 20-50 s and remained relatively constant until the next breath. Furthermore, we successfully monitored the heart rate of a free-swimming Risso's dolphin. The all-in-one suction cup device is feasible for field use without restraining animals and is helpful in further understanding the diving physiology of free-ranging cetaceans. This article is part of the theme issue 'Measuring physiology in free-living animals (Part II)'.

The physiological mechanisms by which animals regulate energy expenditure, respond to stimuli and stressors, and maintain homeostasis at the tissue, organ and whole organism levels can be described by 'physiologging'-that is, the use of onboard miniature electronic devices to record physiological metrics of animals in captivity or free-living in the wild. Despite its origins in the 1960s, physiologging has evolved more slowly than its umbrella field of biologging. However, the recording of physiological metrics in free-living animals will be key to solving some of the greatest challenges in biodiversity conservation, issues pertaining to animal health and welfare, and for inspiring future therapeutic strategies for human health. Current physiologging technologies encompass the measurement of physiological variables such as heart rate, brain activity, body temperature, muscle stimulation and dynamic movement, yet future developments will allow for onboard logging of metrics relating to organelle, molecular and genetic function. This article is part of the theme issue 'Measuring physiology in free-living animals (Part II)'.

Thus far, ecophysiology research has predominantly been conducted within controlled laboratory-based environments, owing to a mismatch between the recording technologies available for physiological monitoring in wild animals and the suite of behaviours and environments they need to withstand, without unduly affecting subjects. While it is possible to record some physiological variables for free-living animals using animal-attached logging devices, including inertial-measurement, heart-rate and temperature loggers, the field is still in its infancy. In this opinion piece, we review the most important future research directions for advancing the field of 'physiologging' in wild animals, including the technological development that we anticipate will be required, and the fiscal and ethical challenges that must be overcome. Non-invasive, multi-sensor miniature devices are ubiquitous in the world of human health and fitness monitoring, creating invaluable opportunities for animal and human physiologging to drive synergistic advances. We argue that by capitalizing on the research efforts and advancements made in the development of human wearables, it will be possible to design the non-invasive loggers needed by ecophysiologists to collect accurate physiological data from free-ranging animals ethically and with an absolute minimum of impact. In turn, findings have the capacity to foster transformative advances in human health monitoring. Thus, we invite biomedical engineers and researchers to collaborate with the animal-tagging community to drive forward the advancements necessary to realize the full potential of both fields. This article is part of the theme issue 'Measuring physiology in free-living animals (Part II)'.

Drawing on insights from qualitative social science research, this paper aims to prompt reflection on social, ethical and regulatory challenges faced by scientists undertaking invasive animal research in the field and propose ways of addressing these challenges to promote good care for animals and environments. In particular, we explore challenges relating to the management of (i) relationships with publics and stakeholders, who may be present at field sites or crucial to research success; (ii) ethical considerations not present in the laboratory, such as the impacts of research on populations and ecosystems; (iii) working under an array of regulations, which may operate in accordance with competing ethical principles or objectives; and (iv) relationships with regulators (especially vets), which may involve disagreements over ethics and expertise, especially because regulators may be more accustomed to overseeing research in the laboratory than the field. We argue that flexibility-at a personal and policy level-and respect for others' expertise emerged as two key ways of negotiating ethical challenges, fostering positive working relationships and promoting good care for individual animals and broader ecosystems. While our analysis focuses on the UK, we propose that many of these lessons are broadly applicable to international contexts. This article is part of the theme issue 'Measuring physiology in free-living animals (Part II)'.

Recent advances in tagging and biologging technology have yielded unprecedented insights into wild animal physiology. However, time-series data from such wild tracking studies present numerous analytical challenges owing to their unique nature, often exhibiting strong autocorrelation within and among samples, low samples sizes and complicated random effect structures. Gleaning robust quantitative estimates from these physiological data, and, therefore, accurate insights into the life histories of the animals they pertain to, requires careful and thoughtful application of existing statistical tools. Using a combination of both simulated and real datasets, I highlight the key pitfalls associated with analysing physiological data from wild monitoring studies, and investigate issues of optimal study design, statistical power, and model precision and accuracy. I also recommend best practice approaches for dealing with their inherent limitations. This work will provide a concise, accessible roadmap for researchers looking to maximize the yield of information from complex and hard-won biologging datasets. This article is part of the theme issue 'Measuring physiology in free-living animals (Part II)'.

The latest technologies associated with implantable physiological monitoring devices can record multiple channels of data (including: heart rates and rhythms, activity, temperature, impedance and posture), and coupled with powerful software applications, have provided novel insights into the physiology of animals in the wild. This perspective details past challenges and lessons learned from the uses and developments of implanted biologgers designed for human clinical application in our research on free-ranging American black bears ( Ursus americanus ). In addition, we reference other research by colleagues and collaborators who have leveraged these devices in their work, including: brown bears ( Ursus arctos ), grey wolves ( Canis lupus ), moose ( Alces alces ), maned wolves ( Chrysocyon brachyurus ) and southern elephant seals ( Mirounga leonina ). We also discuss the potentials for applications of such devices across a range of other species. To date, the devices described have been used in fifteen different wild species, with publications pending in many instances. We have focused our physiological research on the analyses of heart rates and rhythms and thus special attention will be paid to this topic. We then discuss some major expected step changes such as improvements in sensing algorithms, data storage, and the incorporation of next-generation short-range wireless telemetry. The latter provides new avenues for data transfer, and when combined with cloud-based computing, it not only provides means for big data storage but also the ability to readily leverage high-performance computing platforms using artificial intelligence and machine learning algorithms. These advances will dramatically increase both data quantity and quality and will facilitate the development of automated recognition of extreme physiological events or key behaviours of interest in a broad array of environments, thus further aiding wildlife monitoring and management. This article is part of the theme issue 'Measuring physiology in free-living animals (Part I)'.

To measure the heart rate of unrestrained sea turtles, it has been believed that a probe must be inserted inside the body owing to the presence of the shell. However, inserting the probe is invasive and difficult to apply to animals in the field. Here, we have developed a non-invasive heart rate measurement method for some species of sea turtles. In our approach, an electrocardiogram (ECG) was performed using an animal-borne ECG recorder and two electrodes-which were electrically insulated from seawater-pasted on the carapace. Based on the measured ECG, the heartbeat signals were identified with an algorithm using a band-pass filter. We implemented this algorithm in a user-friendly program package, ECGtoHR. In experiments conducted in a water tank and in a lagoon, we successfully measured the heart rate of loggerhead, olive ridley and black turtles, but not green and hawksbill turtles. The average heart rate of turtles when resting underwater was 6.2 ± 1.9 beats min -1 and that when moving at the surface was 14.0 ± 2.4 beats min -1 . Our approach is particularly suitable for endangered species such as sea turtles, and has the potential to be extended to a variety of other free-ranging species. This article is part of the theme issue 'Measuring physiology in free-living animals (Part I)'.

By describing where animals go, biologging technologies (i.e. animal attached logging of biological variables with small electronic devices) have been used to document the remarkable athletic feats of wild animals since the 1940s. The rapid development and miniaturization of physiologging (i.e. logging of physiological variables such as heart rate, blood oxygen content, lactate, breathing frequency and tidal volume on devices attached to animals) technologies in recent times (e.g. devices that weigh less than 2 g mass that can measure electrical biopotentials for days to weeks) has provided astonishing insights into the physiology of free-living animals to document how and why wild animals undertake these extreme feats. Now, physiologging, which was traditionally hindered by technological limitations, device size, ethics and logistics, is poised to benefit enormously from the on-going developments in biomedical and sports wearables technologies. Such technologies are already improving animal welfare and yield in agriculture and aquaculture, but may also reveal future pathways for therapeutic interventions in human health by shedding light on the physiological mechanisms with which free-living animals undertake some of the most extreme and impressive performances on earth. This article is part of the theme issue 'Measuring physiology in free-living animals (Part I)'.

Sensory ecology and physiology of free-ranging animals is challenging to study but underpins our understanding of decision-making in the wild. Existing non-invasive human biomedical technology offers tools that could be harnessed to address these challenges. Functional near-infrared spectroscopy (fNIRS), a wearable, non-invasive biomedical imaging technique measures oxy- and deoxyhaemoglobin concentration changes that can be used to detect localized neural activation in the brain. We tested the efficacy of fNIRS to detect cortical activation in grey seals ( Halichoerus grypus ) and identify regions of the cortex associated with different senses (vision, hearing and touch). The activation of specific cerebral areas in seals was detected by fNIRS in responses to light (vision), sound (hearing) and whisker stimulation (touch). Physiological parameters, including heart and breathing rate, were also extracted from the fNIRS signal, which allowed neural and physiological responses to be monitored simultaneously. This is, to our knowledge, the first time fNIRS has been used to detect cortical activation in a non-domesticated or laboratory animal. Because fNIRS is non-invasive and wearable, this study demonstrates its potential as a tool to quantitatively investigate sensory perception and brain function while simultaneously recording heart rate, tissue and arterial oxygen saturation of haemoglobin, perfusion changes and breathing rate in free-ranging animals. This article is part of the theme issue 'Measuring physiology in free-living animals (Part I)'.

2D monolayer gastric organoids (2DMGOs)-on-a-chip have consistent structures and can live for more than a year in culture. This state-of-the-art cell physiological system in a microfluidic device provides a way to investigate biomedically relevant, stimuli-dependent cellular responses in a variety of differentiated 2DMGOs., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Multiorgan-on-a-chip (multi-OoC) platforms have great potential to redefine the way in which human health research is conducted. After briefly reviewing the need for comprehensive multiorgan models with a systemic dimension, we highlight scenarios in which multiorgan models are advantageous. We next overview existing multi-OoC platforms, including integrated body-on-a-chip devices and modular approaches involving interconnected organ-specific modules. We highlight how multi-OoC models can provide unique information that is not accessible using single-OoC models. Finally, we discuss remaining challenges for the realization of multi-OoC platforms and their worldwide adoption. We anticipate that multi-OoC technology will metamorphose research in biology and medicine by providing holistic and personalized models for understanding and treating multisystem diseases., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Organoids are self-organising stem cell-derived ex vivo cultures widely adopted as biomimetic models of healthy and diseased tissues. Traditional low-dimensional experimental methods such as microscopy and bulk molecular analysis have generated remarkable biological insights from organoids. However, as complex heterocellular systems, organoids are especially well-positioned to take advantage of emerging high-dimensional technologies. In particular, single-cell methods offer considerable opportunities to analyse organoids at unprecedented scale and depth, enabling comprehensive characterisation of cellular processes and spatial organisation underpinning organoid heterogeneity. This review evaluates state-of-the-art analytical methods applied to organoids, discusses the latest advances in single-cell technologies, and speculates on the integration of these two rapidly developing fields., (Crown Copyright © 2020. Published by Elsevier Ltd. All rights reserved.)

In current clinical settings, typically pain is measured by a patient's self-reported information. This subjective pain assessment results in suboptimal treatment plans, over-prescription of opioids, and drug-seeking behavior among patients. In the present study, we explored automatic objective pain intensity estimation machine learning models using inputs from physiological sensors. This study uses BioVid Heat Pain Dataset. We extracted features from Electrodermal Activity (EDA), Electrocardiogram (ECG), Electromyogram (EMG) signals collected from study participants subjected to heat pain. We built different machine learning models, including Linear Regression, Support Vector Regression (SVR), Neural Networks and Extreme Gradient Boosting for continuous value pain intensity estimation. Then we identified the physiological sensor, feature set and machine learning model that give the best predictive performance. We found that EDA is the most information-rich sensor for continuous pain intensity prediction. A set of only 3 features from EDA signals using SVR model gave an average performance of 0.93 mean absolute error (MAE) and 1.16 root means square error (RMSE) for the subject-independent model and of 0.92 MAE and 1.13 RMSE for subject-dependent. The MAE achieved with signal-feature-model combination is less than 1 unit on 0 to 4 continues pain scale, which is smaller than the MAE achieved by the methods reported in the literature. These results demonstrate that it is possible to estimate pain intensity of a patient using a computationally inexpensive machine learning model with 3 statistical features from EDA signal which can be collected from a wrist biosensor. This method paves a way to developing a wearable pain measurement device., Competing Interests: The authors have declared that no competing interests exist.

Flexible electronic sensors composed of conductive material and flexible film have attracted increasing attention in decades due to its commercial, medical and scientific value. However, the poor interfacial bonding robustness between conductive materials and flexible film influences widely practical application of sensors. It is still a great challenge to fabricate a self-adhesive conductive film. Herein, we report a freestanding and self-adhesive bovine serum albumin/polypyrrole (BSA/PPy) hybrid film at the air/water interface. It is discovered that the PPy nanoparticles aggregate uniformly on the BSA film that is formed by amyloid-like BSA aggregation. The BSA/PPy film was integrated with polydimethylsiloxane (PDMS) film to fabricate flexible electronic sensors. The test indicates that the BSA/PPy film-based sensor could tolerate 500 cycles of bending without the resistance performance variation. The BSA/PPy film functions as a key mediator to dynamically tune the PPy conductance in response to external pressures and strains. The sensors exhibit ability for detecting tiny acoustic vibration, real-time human motion, physiological behavior and for differentiating various breathing pattern. Our strategy may open a pathway to readily construct flexible electronic sensors toward practical applications., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Background: An intragastric satiety-inducing device (ISD) (Full Sense Device; Baker, Foote, Kemmeter, Walburn, LLC, Grand Rapids, MI) is a novel weight-loss device, which may induce satiety by applying continuous pressure on the gastric cardia. This study investigated the effect of the ISD on food intake and body weight gain in a rodent model., Methods: Thirty-two male Sprague-Dawley rats (weight, 250-300 g) were randomly divided into four groups of eight individuals. Single-disk (SD) and double-disk (DD) group animals underwent peroral placement of a single- or double-disk ISD, respectively, under fluoroscopic guidance. The ISD comprised a 4 mm × 1.5 cm nitinol stent placed in the lower esophagus and one (single-disk) or two (double-disk) 2.5-cm-diameter star-shaped nitinol disks placed in the gastric fundus. Esophageal stent (ES) and sham-operated (SO) group animals underwent peroral placement of the ES part of the ISD and a sham operation, respectively., Results: Food intake was significantly different among the four groups over the 4-week study period (P < 0.001); food intake was significantly lower in the SD and DD groups than in the SO group (P = 0.016 and P = 0.002, respectively) but was not significantly different between the SD and DD groups (P > 0.999) and between the ES and SO groups (P = 0.677). Body weight was significantly different among the four groups by the end of the study period (P < 0.001); body weight was significantly lower in the DD group than in the SD, ES, and SO groups (P = 0.010, P < 0.001, and P < 0.001, respectively) and in the SD group than in the SO group (P = 0.001), but it was not significantly different between the ES and SO groups (P = 0.344)., Conclusion: ISD reduced food intake and suppressed body weight gain in a rodent model.

Animal behavior is an essential element in behavioral neuroscience study. However, most behavior studies in small animals such as fruit flies ( Drosophila melanogaster ) have been performed in a limited spatial chamber or by tethering the fly's body on a fixture, which restricts its natural behavior. In this paper, we developed the Transparent Omnidirectional Locomotion Compensator (TOLC) for a freely walking fruit fly without tethering, which enables its navigation in infinite space. The TOLC maintains a position of a fruit fly by compensating its motion using the transparent sphere. The TOLC is capable of maintaining the position error < 1 mm for 90.3% of the time and the heading error < 5° for 80.2% of the time. The inverted imaging system with a transparent sphere secures the space for an additional experimental apparatus. Because the proposed TOLC allows us to observe a freely walking fly without physical tethering, there is no potential injury during the experiment. Thus, the TOLC will offer a unique opportunity to investigate longitudinal studies of a wide range of behavior in an unrestricted walking Drosophila .

A modified protocol for the extraction and analysis of cortisol in individual zebrafish, Danio rerio , embryo, and larva samples has been developed and evaluated. Recovery efficiency of the method was high, specifically calculated at 93.8% ± 6.5%. Dilution tests showed high parallelism, while increasing the number of individuals used in each extraction sample resulted in a linear, although slightly underestimated, increase of cortisol yield. Results of cortisol content from 0, 3, and 5 days postfertilization (dpf) fish using the proposed protocol were within the range of most published studies analyzing cortisol in pooled samples of 10-30 individuals. Moreover, 5 dpf larvae had significantly higher cortisol levels than embryos, a pattern commonly observed in literature. Finally, application of an osmotic stress in 5 dpf larvae led to a statistically significant increase in cortisol content.

The 2019 Nobel Prize for Medicine or Physiology was assigned to three prestigious physician-scientists, Gregg L. Semenza, William G. Kaelin, and Peter J. Ratcliffe, who clarified the molecular mechanisms of hypoxia adaptation. This viewpoint traces their fundamental findings, which have paved the way for the development of innovative drugs for a wide range of common diseases, including cancer and anemia.

Quantifying how whole organisms respond to challenges in the external and internal environment ("stressors") is difficult. To date, physiological ecologists have mostly used measures of glucocorticoids (GCs) to assess the impact of stressors on animals. This is of course too simplistic as Hans Seyle himself characterized the response of organisms to "noxious stimuli" using multiple physiological responses. Possible solutions include increasing the number of biomarkers to more accurately characterize the "stress state" of animal or just measuring different biomarkers to more accurately characterize the degree of acute or chronic stressors an animal is experiencing. We focus on the latter and discuss how heart rate (HR) and heart rate variability (HRV) may be better predictors of the degree of activation of the sympathetic-adrenal-medullary system and complement or even replace measures of GCs as indicators of animal health, welfare, fitness, or their level of exposure to stressors. The miniaturization of biological sensor technology ("bio-sensors" or "bio-loggers") presents an opportunity to reassess measures of stress state and develop new approaches. We describe some modern approaches to gathering these HR and HRV data in free-living animals with the aim that heart dynamics will be more integrated with measures of GCs as bio-markers of stress state and predictors of fitness in free-living animals., (© The Author(s) 2020. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.)

The importance of estimating human movement has increased in the field of human motion capture. HTC VIVE is a popular device that provides a convenient way of capturing human motions using several sensors. Recently, the motion of only users' hands has been captured, thereby greatly reducing the range of motion captured. This paper proposes a framework to estimate single-arm orientations using soft sensors mainly by combining a Bi-long short-term memory (Bi-LSTM) and two-layer LSTM. Positions of the two hands are measured using an HTC VIVE set, and the orientations of a single arm, including its corresponding upper arm and forearm, are estimated using the proposed framework based on the estimated positions of the two hands. Given that the proposed framework is meant for a single arm, if orientations of two arms are required to be estimated, the estimations are performed twice. To obtain the ground truth of the orientations of single-arm movements, two Myo gesture-control sensory armbands are employed on the single arm: one for the upper arm and the other for the forearm. The proposed framework analyzed the contextual features of consecutive sensory arm movements, which provides an efficient way to improve the accuracy of arm movement estimation. In comparison with the ground truth, the proposed method estimated the arm movements using a dynamic time warping distance, which was the average of 73.90% less than that of a conventional Bayesian framework. The distinct feature of our proposed framework is that the number of sensors attached to end-users is reduced. Additionally, with the use of our framework, the arm orientations can be estimated with any soft sensor, and good accuracy of the estimations can be ensured. Another contribution is the suggestion of the combination of the Bi-LSTM and two-layer LSTM.

Purpose: A novel portable system has been used to evaluate spatial knee movement, but its accuracy and repeatability is not known. The aim of this study was to investigate the accuracy and repeatability of the measurement., Methods: Ten healthy participants were included, and the knee motion trajectory during walking were assessed. Six evaluations were conducted (three days by two raters) for each participant. The motion parameters at the key points and the range of motion were statistically analyzed. Intraclass correlation coefficients (ICC), standard error of the measurement (SEM), and the Bland-Altman method were used., Results: For intra-rater repeatability, 1) the ICC values range from 0.75 to 0.9 for rotations; and 0.64 to 0.96 for translations. Among the ICC values, 100% of rotations and 90% of translations were not less than 0.70; 2) among the SEM values, 100% of rotations were not more than 5°, while 73.3% of translations were less than 3 mm. For inter-rater repeatability, 1) the ICC values range from 0.68 to 0.99 for rotations; and 0.57 to 0.93 for translations. Among the ICC values, 95.6% of rotations and 82.2% of translations were not less than 0.70; 2) among the SEM values, 100% of rotations were not more than 5°, and 48.9% of translations were less than 3 mm. The Bland-Altman plots showed good agreement for intra- and inter- repeatability., Conclusions: The results indicated that the accuracy and repeatability of the measurement were acceptable, except for the inter-rater repeatability for translation. This may help researchers and physicians better interpret the measurement data.

Purpose: The aim of this study was to analyse absolute and relative reliability of a number of postural static stability measures obtained from a GYKO inertial sensor system in young adults., Methods: The study examined 29 healthy non-athlete young adults. A test was performed for 30 s while standing on one foot, without moving, with eyes open and arms relaxed along the sides of the body. The examinations were performed twice, with a one-week interval. Relative reliability was measured using the intraclass correlation coefficient (ICC) and the 95% confidence interval (95% CI), whereas the absolute reliability was evaluated based on the standard error of measurement (SEM) and the minimal detectable change (MDC)., Results: The results of this study showed moderate to good relative reliability scores for all the postural stability measures, with ICC values ranging from 0.62 to 0.70. For most of the analysed variables, SEM% ranged from ca. 10 to 14%. Relatively high SEM% values were obtained only for two variables (Area, Convex Hull Area)., Conclusions: The low costs of GYKO inertial sensor systems, the fast and easy installation, the mobility and high reliability of the measurement of postural stability show that it can be effective alternative to stabilographic platforms.

Objectives : Current literature is scarce about the use of an inertial sensor to measure cervical active range of motion (aROM). The objective of the present study is to determine inter- and intra-reliability in the measurement of cervical aROM using inertial sensors in asymptomatic individuals. Materials and methods : Twenty asymptomatic individuals participated in the study. Two different physiotherapists measured each participant for cervical aROM (6 movements). The sequence of movements and the explanations given were standardized. The rater's order of measurement was randomized. Results : For the intra-rater results, the intraclass correlation coefficient (ICC) values for all cervical movements were good for Rater A (ICC >0.90) and Rater B (ICC >0.90). For the inter-rater results, the ICC values were above 0.75 for all movements, indicating a good level of reliability. Also, values obtained in SEM, MDC 90 and LOA indicate good agreement. Conclusion : The data obtained in this study suggest that inertial sensors can be used in clinics due to their high intra- and inter-rater ICC (>0.80). Also, its low economic cost, easy handling, and various utilities make this tool a useful alternative in the measurement of cervical aROM.

The stomach is a major digestive organ of the human body that plays a role in storing, mixing, reducing chylous particles and breaking down ingested foods. This study established a new artificial gastric digestive system (AGDS) with a human stomach shape and structure by a 3D digital technology. Two sets of symmetrical rollers and one set of contrary movement of the roller were used to simulate the peristalsis of the stomach, and a pH-stat workstation was applied to control the pH. The force, pepsin and gastric juice secretion, gastric emptying and pH changes of AGDS were tacked and validated. Besides, the digestion behavior of α-lactalbumin using AGDS model, static model and semi-dynamic model (pH and enzyme changes) were studied. The results showed that the hydrolysis and morphology of protein, peptide and amino acids accumulation obtained by AGDS were different from the static digestion and semi-dynamic digestion models, indicating pH and gastric motility had certain effect on protein hydrolysis, particularly in the pepsin activity changes at early stage of digestion. AGDS, verified by mechanical analysis and in vitro digestion experiments, indicated that it can provide α-LA protein solution with a true and reliable digestion profile in the stomach, and can be used as a potential dynamic gastric digestion model for the food development., (Copyright © 2019. Published by Elsevier Ltd.)

Non-shivering thermogenesis (NST) is a metabolic response to acute cold exposure that involves the liberation of chemical energy through physiological mechanisms that are separate from muscle shivering. Recent research suggests that the metabolic and endocrine action of brown adipose tissue (BAT) may play an important role in adult human NST. Thus, characterizing variation in BAT across human populations is of central importance to human biologists interested in human energetics and cardio-metabolic health. The gold standard for measuring BAT requires positron emission tomography (PET) and computed tomography (CT)-a technique that is expensive, exposes the participant to radiation, and is inaccessible to researchers working in many regions. Here, the author outline a noninvasive, portable alternative approach to quantifying BAT that modifies the protocols commonly used in PET/CT studies. The method consists of three components: (a) activating BAT thermogenesis using a mild cooling condition; (b) indirectly quantifying BAT thermogenesis by measuring the change in skin temperature where BAT is commonly stored using infrared thermal imaging; and (c) estimating NST by measuring the change in energy expenditure using open-circuit indirect calorimetry. The development of "field-friendly" methods will allow human biologists to better characterize population variation in BAT as well as its adaptive and health significance., (© 2019 Wiley Periodicals, Inc.)

Objective: The present study reports the on-field screening of a population of young soccer players in the pursuit of alterations in gait using a portable and low-cost gait analysis system composed of a Wii Balance Board and a webcam., Results: Recordings of motion of the lower extremities along with vertical ground reaction force (GRF) were used to quantify coefficients of symmetry for the overall GRF and the forces exerted by the quadriceps femori and acting on the anterior cruciate ligament (ACL). Data show that, in face of a quite homogeneous symmetry of GRF during left and right stance phases of gait, quadriceps and ACL exert and are subjected to left-right asymmetrical forces that might prelude, especially in young athletes, later alterations of gait.

Background: Clinical assessment of skin stiffness is unreliable in many applications. The durometer, an industrial device to measure hardness, has previously been applied in scleroderma. The Myoton is a noninvasive handheld device for assessing soft tissue biomechanical parameters., Materials and Methods: We evaluated the reproducibility of both devices in six healthy subjects in the volar forearm, dorsal forearm, upper arm, shin, and calf bilaterally. The intraclass correlation coefficient (ICC) was used as a measure of reproducibility among three observers., Results: The interobserver intraclass correlation coefficient (ICC) of overall stiffness for the Myoton was 0.74 [95% confidence interval (CI) 0.45-1.00] and 0.71 [0.39-1.00] for the durometer. Coefficient of variation (CV) for the Myoton was 6.4% [range 1.3-12.1] and 7.6% [range 4.4-13.8] for the durometer. Myoton and durometer values had a Pearson correlation of 0.69. The intraobserver Myoton ICC was 0.89 [0.74-1.00] and CV 3.1% [range 1.6-5.0]. The 95% confidence minimal detectable change by the Myoton for a single observer is 32.4 N/m, which is 7.6% of the average subject's overall stiffness., Conclusion: The Myoton demonstrated high reproducibility, particularly in the overall stiffness parameter, and merits further investigation to assess disease progression and treatment efficacy., (Published 2018. This article has been contributed to by US Government employees and their work is in the public domain in the USA.)

Sonomicrometry is widely applied in biomechanics and physiology to measure precise distances with high temporal resolution. Although commonly used, its usefulness is often limited by the presence of artifacts that require correction. Unfortunately, procedures reported in the literature for artifact correction are often unclear. Furthermore, currently available tools for artifact correction require significant manual manipulations, the consistency of which takes painstaking effort to verify. To improve the efficiency and consistency of sonomicrometry, we have developed a new software tool for the correction of sonomicrometry artifacts. This tool provides a framework for artifact correction requiring fewer and more limited manipulations from the user. We aimed to make this tool more transparent and easier to use than commercially available tools. To facilitate its application, we describe the relevant properties of sonomicrometry artifacts and detail the software's correction algorithm. The software is available for MacOS and Linux with source code and documentation., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2018. Published by The Company of Biologists Ltd.)

Measurement of rates of oxygen consumption ( Mo 2 ) in small aquatic embryos or larvae (<1 mm) in response to altered environmental conditions has traditionally been challenging. Here, using modifications of a commercially available fluorescent optode flow-through cell (FTC; PreSens FTC-PSt3) and routine laboratory supplies (syringes, stopcocks, tubing), we have constructed a manual intermittent flow respirometer (MIFR) that allows measurement of Mo 2 in small numbers of individuals when sequentially exposed to different environmental conditions (e.g., changes in seawater pH) through a gravity-driven media replacement perfusion system. We first show that the FTC can be used in "static" mode while incubating small numbers of embryos/larvae contained within the planar oxygen sensor (POS) chamber with Nitex filters. We then demonstrate the use of the MIFR by exposing larval echinoderms ( Fellaster zelandiae, Evechinus chloroticus, and Centrostephanus rodgersii) to seawater equilibrated with elevated CO 2 and measured Mo 2 during acute and chronic exposure to hypercapnia. This MIFR method will allow investigators to address questions regarding the respiratory physiology of small aquatic animals, such as the thresholds for metabolic depression in embryonic and larval forms. NEW & NOTEWORTHY A manual intermittent flow respirometer (MIFR), allowing media exchange in a flow-through cell containing small aquatic organisms, permits repeated measurement of Mo 2 of individuals not only in a single medium (e.g., technical replication), but also in different media (here, high CO 2 -equilibrated seawater), enabling measurement of acute physiological responses to changed conditions. This versatile technique has wide-ranging implications for the study of the Mo 2 response of aquatic organisms in the face of climate change.

Stair running, both ascending and descending, is a challenging aerobic exercise that many athletes, recreational runners, and soldiers perform during training. Studying biomechanics of stair running over multiple steps has been limited by the practical challenges presented while using optical-based motion tracking systems. We propose using foot-mounted inertial measurement units (IMUs) as a solution as they enable unrestricted motion capture in any environment and without need for external references. In particular, this paper presents methods for estimating foot velocity and trajectory during stair running using foot-mounted IMUs. Computational methods leverage the stationary periods occurring during the stance phase and known stair geometry to estimate foot orientation and trajectory, ultimately used to calculate stride metrics. These calculations, applied to human participant stair running data, reveal performance trends through timing, trajectory, energy, and force stride metrics. We present the results of our analysis of experimental data collected on eleven subjects. Overall, we determine that for either ascending or descending, the stance time is the strongest predictor of speed as shown by its high correlation with stride time., Competing Interests: The authors declare no conflict of interest.

Increasingly, inertial sensors are being used for running analyses. The aim of this study was to systematically investigate the influence of inertial sensor sampling frequencies (SF) on the accuracy of kinematic, spatio-temporal, and kinetic parameters. We hypothesized that running analyses at lower SF result in less signal information and therefore the inability to sufficiently interpret measurement data. Twenty-one subjects participated in this study. Rearfoot strikers ran on an indoor running track at a velocity of 3.5 ± 0.1 ms -1 . A uniaxial accelerometer was attached at the tibia and an inertial measurement unit was mounted at the heel of the right shoe. All sensors were synchronized at the start and data was measured with 1000 Hz (reference SF). Datasets were reduced to 500, 333, 250, 200, and 100 Hz in post-processing. The results of this study showed that a minimum SF of 500 Hz should be used to accurately measure kinetic parameters (e.g. peak heel acceleration). In contrast, stride length showed accurate results even at 333 Hz. 200 Hz were required to calculate parameters accurately for peak tibial acceleration, stride duration, and all kinematic measurements. The information from this study is necessary to correctly interpret measurement data of existing investigations and to plan future studies.

Measurement of the ground reaction forces (GRF) during walking is typically limited to laboratory settings, and only short observations using wearable pressure insoles have been reported so far. In this study, a new proxy measurement method is proposed to estimate the vertical component of the GRF (vGRF) from wearable accelerometer signals. The accelerations are used as the proxy variable. An orthogonal forward regression algorithm (OFR) is employed to identify the dynamic relationships between the proxy variables and the measured vGRF using pressure-sensing insoles. The obtained model, which represents the connection between the proxy variable and the vGRF, is then used to predict the latter. The results have been validated using pressure insoles data collected from nine healthy individuals under two outdoor walking tasks in non-laboratory settings. The results show that the vGRFs can be reconstructed with high accuracy (with an average prediction error of less than 5.0%) using only one wearable sensor mounted at the waist (L5, fifth lumbar vertebra). Proxy measures with different sensor positions are also discussed. Results show that the waist acceleration-based proxy measurement is more stable with less inter-task and inter-subject variability than the proxy measures based on forehead level accelerations. The proposed proxy measure provides a promising low-cost method for monitoring ground reaction forces in real-life settings and introduces a novel generic approach for replacing the direct determination of difficult to measure variables in many applications., Competing Interests: The authors declare no conflict of interest.

Ammonia is one of the members of odor gases and a possible source of odor in indoor environment. However, little has been known on the actual emission rate of ammonia from the human skin surface. Then, this study aimed to estimate the whole-body dermal emission rate of ammonia by simultaneous and multi-point measurement of emission fluxes of ammonia employing a passive flux sampler - ion chromatography system. Firstly, the emission fluxes of ammonia were non-invasively measured for ten volunteers at 13 sampling positions set in 13 anatomical regions classified by Kurazumi et al. The measured emission fluxes were then converted to partial emission rates using the surface body areas estimated by weights and heights of volunteers and partial rates of 13 body regions. Subsequent summation of the partial emission rates provided the whole body dermal emission rate of ammonia. The results ranged from 2.9 to 12mgh -1 with an average of 5.9±3.2mgh -1 per person for the ten healthy young volunteers. The values were much greater than those from human breath, and thus the dermal emission of ammonia was found more significant odor source than the breath exhalation in indoor environment., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The Douglas bag technique is reviewed as one in a series of articles looking at historical insights into measurement of whole body metabolic rate. Consideration of all articles looking at Douglas bag technique and chemical gas analysis has here focused on the growing appreciation of errors in measuring expired volumes and gas composition, and subjective reactions to airflow resistance and dead space. Multiple small sources of error have been identified and appropriate remedies proposed over a century of use of the methodology. Changes in the bag lining have limited gas diffusion, laboratories conducting gas analyses have undergone validation, and WHO guidelines on airflow resistance have minimized reactive effects. One remaining difficulty is a contamination of expirate by dead space air, minimized by keeping the dead space <70 mL. Care must also be taken to ensure a steady state, and formal validation of the Douglas bag method still needs to be carried out. We may conclude that the Douglas bag method has helped to define key concepts in exercise physiology. Although now superceded in many applications, the errors in a meticulously completed measurement are sufficiently low to warrant retention of the Douglas bag as the gold standard when evaluating newer open-circuit methodology.

A sedentary lifestyle and lack of physical activity are well-established risk factors for chronic disease and adverse health outcomes. Thus, there is enormous interest in measuring physical activity in biomedical research. Many consumer physical activity monitors, including Basis Health Tracker, BodyMedia Fit, DirectLife, Fitbit Flex, Fitbit One, Fitbit Zip, Garmin Vivofit, Jawbone UP, MisFit Shine, Nike FuelBand, Polar Loop, Withings Pulse O 2 , and others have accuracies similar to that of research-grade physical activity monitors for measuring steps. This review focuses on the unprecedented opportunities that consumer physical activity monitors offer for human physiology and pathophysiology research because of their ability to measure activity continuously under real-life conditions and because they are already widely used by consumers. We examine current and potential uses of consumer physical activity monitors as a measuring or monitoring device, or as an intervention in strategies to change behavior and predict health outcomes. The accuracy, reliability, reproducibility, and validity of consumer physical activity monitors are reviewed, as are limitations and challenges associated with using these devices in research. Other topics covered include how smartphone apps and platforms, such as the Apple ResearchKit, can be used in conjunction with consumer physical activity monitors for research. Lastly, the future of consumer physical activity monitors and related technology is considered: pattern recognition, integration of sleep monitors, and other biosensors in combination with new forms of information processing., (Copyright © 2017 the American Physiological Society.)

Noseband tightness is difficult to assess in horses participating in equestrian sports such as dressage, show jumping and three-day-eventing. There is growing concern that nosebands are commonly tightened to such an extent as to restrict normal equine behaviour and possibly cause injury. In the absence of a clear agreed definition of noseband tightness, a simple model of the equine nose-noseband interface environment was developed in order to guide further studies in this area. The normal force component of the noseband tensile force was identified as the key contributor to sub-noseband tissue compression. The model was used to inform the design of a digital tightness gauge which could reliably measure the normal force component of the noseband tensile force. A digital tightness gauge was developed to measure this parameter under nosebands fitted to bridled horses. Results are presented for field tests using two prototype designs. Prototype version three was used in field trial 1 (n = 15, frontal nasal plane sub-noseband site). Results of this trial were used to develop an ergonomically designed prototype, version 4, which was tested in a second field trial (n = 12, frontal nasal plane and lateral sub-noseband site). Nosebands were set to three tightness settings in each trial as judged by a single rater using an International Society for Equitation Science (ISES) taper gauge. Normal forces in the range 7-95 N were recorded at the frontal nasal plane while a lower range 1-28 N was found at the lateral site for the taper gauge range used in the trials. The digital tightness gauge was found to be simple to use, reliable, and safe and its use did not agitate the animals in any discernable way. A simple six point tightness scale is suggested to aid regulation implementation and the control of noseband tightness using normal force measurement as the objective tightness discriminant., Competing Interests: GM is owner/director of Aaron Value Adding Services Ltd. The company provides an electronic printed circuit board production and prototyping service. The company manufactured, validated and performed preliminary circuit tests on the digital tightness gauge printed circuit boards used in this project. VC, TC, RC and OD are listed as inventors on a patent application filed with the Irish Patent Office relating to the noseband digital tightness gauge (cited in the manuscript). This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Dark respiration measurements with open-flow gas exchange analyzers are often questioned for their low accuracy as their low values often reach the precision limit of the instrument. Respiration was measured in five species, two hypostomatous (Vitis Vinifera L. and Acanthus mollis) and three amphistomatous, one with similar amount of stomata in both sides (Eucalyptus citriodora) and two with different stomata density (Brassica oleracea and Vicia faba). CO 2 differential (ΔCO 2 ) increased two-fold with no change in apparent R d , when the two leaves with higher stomatal density faced outside. These results showed a clear effect of the position of stomata on ΔCO 2 . Therefore, it can be concluded that leaf position is important to guarantee the improvement of respiration measurements increasing ΔCO 2 without affecting the respiration results by leaf or mass units. This method will help to increase the accuracy of leaf respiration measurements using gas exchange analyzers., (Copyright © 2016 Elsevier GmbH. All rights reserved.)

Accelerometers are incorporated into many consumer devices providing new ways to monitor gait, mobility, and fall risk. However, many health benefits have not been realised because of issues with data quality that results from gravitational 'cross-talk' when the wearable device is tilted. Here we present an adaptive filter designed to improve the quality of accelerometer data prior to measuring dynamic pelvic sway patterns during a six minute walk test in people with and without Multiple Sclerosis (MS). Optical motion capture was used as the gold standard. Improved wearable device accuracy (≤4.4% NRMSE) was achieved using gyroscopic corrections and scaling filter thresholds by step frequency. The people with MS presented significantly greater pelvis sway range to compensate for their lower limb weaknesses and joint contractures. The visualisation of asymmetric pelvic sway in people with MS illustrates the potential to better understand their mobility impairments for reducing fall risk.

This paper presents a method to measure the passive stiffness of an ankle joint in three degrees of freedom (DOF) under two motion speeds (1 Hz and 5 degree/s) using a developed Stewart platform-type device. The developed device can reproduce input motions of the foot in 6 DOF by controlling six pneumatic linear motion actuators. We used the device to measure the passive stiffness of an ankle joint undergoing three kinds of motion, namely dorsi-plantar flexion, inversion-eversion, and adduction-abduction. The measured values of the passive stiffness of the ankle joint in dorsiflexion that we obtained agreed well with that obtained in a previous study, indicating that the developed device is useful for measuring the passive stiffness of ankle joint. In addition, the developed device can be used to measure the stiffness in inversion-eversion and adduction-abduction motions as well, parameters that have never been measured. The results we obtained demonstrated certain interesting features as we varied both the direction and pace of motion (e.g., there were significant differences in the stiffness not only between adduction and abduction during the faster pace, but also between these and the other motions).

The quantification of postural sway during the unipedal stance test is one of the essentials of posturography. A shift of center of pressure (CoP) is an indirect measure of postural sway and also a measure of a person's ability to maintain balance. A widely used method in laboratory settings to calculate the sway of body center of mass (CoM) is through an ellipse that encloses 95% of CoP trajectory. The 95% ellipse can be computed under the assumption that the spatial distribution of the CoP points recorded from force platforms is normal. However, to date, this assumption of normality has not been demonstrated for sway measurements recorded from a sacral inertial measurement unit (IMU). This work provides evidence for non-normality of sway trajectories calculated at a sacral IMU with injured subjects as well as healthy subjects.

Thermoregulatory ability and behavior influence organismal responses to their environment. By measuring thermal preferences, researchers can better understand the effects that temperature tolerances have on ecological and physiological responses to both biotic and abiotic stressors. However, because of funding limitations and confounders, measuring thermoregulation can often be difficult. Here, we provide an effective, affordable (~$50 USD per unit), easy to construct, and validated apparatus for measuring the long-term thermal preferences of animals. In tests, the apparatus spanned temperatures from 9.29 to 33.94°C, and we provide methods to further increase this range. Additionally, we provide simple methods to non-invasively measure animal and substrate temperatures and to prevent temperature preferences of the focal organisms from being confounded with temperature preferences of its prey and its humidity preferences. To validate the apparatus, we show that it was capable of detecting individual-level consistency and among individual-level variation in the preferred body temperatures of Southern toads (Anaxyrus terrestris) and Cuban tree frogs (Osteopilus septentrionalis) over three-weeks. Nearly every aspect of our design is adaptable to meet the needs of a multitude of study systems, including various terrestrial amphibious, and aquatic organisms. The apparatus and methods described here can be used to quantify behavioral thermal preferences, which can be critical for determining temperature tolerances across species and thus the resiliency of species to current and impending climate change., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

In order to perform fall risk assessments using wearable inertial sensors in older adults in their natural settings where falls are likely to occur, a first step is to automatically segment and classify sensor signals of human movements into the known `activities of interest'. Sensor data from such activities can later be used through quantitative and qualitative analysis for differentiating fallers from non-fallers. In this study, ten young adults participated in experimental trials involving several variations of walking, transferring and sedentary activities. Data from tri-axial accelerometers and gyroscopes were used to classify the aforementioned three categories using a multiclass support vector machine algorithm. Our results showed 100% accuracy in distinguishing walking, transferring and sedentary activities using data from a three-sensor combination of sternum and both ankles.

Persons unable to exercise due to old age, immobility or medical condition may develop low bone density, decline in muscle contraction, blood pooling or clot. Due to musculoskeletal fragility caution is required in bone and muscle strengthening. Similarly, caution is required to use anticoagulant drug to prevent blood clot due to side effect, and compression devices are not as effective as drug. This paper presents a transcutaneous muscle fiber excitation system adaptable for use in seated, walking or lying position. Clinical trials will determine performance in pathological cases.

One of the most effective ways of engaging students of physiology and medicine is through laboratory demonstrations and case studies that combine 1) the use of equipment, 2) problem solving, 3) visual representations, and 4) manipulation and interpretation of data. Depending on the measurements made and the type of test, laboratory demonstrations have the added benefit of being able to show multiple organ system integration. Many research techniques can also serve as effective demonstrations of integrative human physiology. The "Duffin" hyperoxic rebreathing test is often used in research settings as a test of central respiratory chemosensitivity and cerebrovascular reactivity to CO2. We aimed to demonstrate the utility of the hyperoxic rebreathing test for both respiratory and cerebrovascular responses to increases in CO2 and illustrate the integration of the respiratory and cerebrovascular systems. In the present article, methods such as spirometry, respiratory gas analysis, and transcranial Doppler ultrasound are described, and raw data traces can be adopted for discussion in a tutorial setting. If educators have these instruments available, instructions on how to carry out the test are provided so students can collect their own data. In either case, data analysis and quantification are discussed, including principles of linear regression, calculation of slope, the coefficient of determination (R(2)), and differences between plotting absolute versus normalized data. Using the hyperoxic rebreathing test as a demonstration of the complex interaction and integration between the respiratory and cerebrovascular systems provides senior undergraduate, graduate, and medical students with an advanced understanding of the integrative nature of human physiology., (Copyright © 2016 The American Physiological Society.)

Since the advent of electromyogram recording, precise measures of tremor and gait have been used to study movement disorders such as Parkinson's disease. Now, a wide range of accelerometers and other motion-tracking technologies exist to better inform researchers and clinicians, yet such systems are rarely tested for accuracy or suitability before use. Our inexpensive test-rig can produce sinusoidal displacements using a simple cantilever system driven by a subwoofer. Controlled sinusoids were generated using computer software, and the displacement amplitudes of the test-rig were verified with fiducial marker tracking. To illustrate the use of the test-rig, we evaluated an accelerometer and an electromagnetic motion tracker. Accelerometry recordings were accurate to within ±0.09 g of actual peak-to-peak amplitude with a frequency response close to unity gain between 1 and 20 Hz. The electromagnetic sensor underestimated peak displacement by 2.68 mm, which was largely due to a diminishing gain with increasing frequency. Both sensors had low distortion. Overall sensitivity was limited by noise for the accelerometer and quantisation resolution for the electromagnetic sensor. Our simple and low-cost test-rig can be used to bench-test sensors used in movement disorders research. It was able to produce reliable sinusoidal displacements and worked across the 1- to 20-Hz frequency range.

This paper briefly presents recent developments in the field of wearable sensors and systems that are relevant to the area of normal and pathological human gait analysis. By using wearable sensors, it is possible to monitor the pathological gait disorders and alterations and the changes of balance in the people and prevent or diagnose of different diseases. The most usable wearable sensors and their applications in clinical field are presented based on specialty literature.

Background: To investigate the relationship between neural function and behavior it is necessary to record neuronal activity in the brains of freely behaving animals, a technique that typically involves tethering to a data acquisition system. Optimally this approach allows animals to behave without any interference of movement or task performance. Currently many laboratories in the cognitive and behavioral neuroscience fields employ commercial motorized commutator systems using torque sensors to detect tether movement induced by the trajectory behaviors of animals., Results: In this study we describe a novel motorized commutator system which is automatically controlled by video tracking. To obtain accurate head direction data two light emitting diodes were used and video image noise was minimized by physical light source manipulation. The system calculates the rotation of the animal across a single trial by processing head direction data and the software, which calibrates the motor rotation angle, subsequently generates voltage pulses to actively untwist the tether. This system successfully provides a tether twist-free environment for animals performing behavioral tasks and simultaneous neural activity recording., Conclusions: To the best of our knowledge, it is the first to utilize video tracking generated head direction to detect tether twisting and compensate with a motorized commutator system. Our automatic commutator control system promises an affordable and accessible method to improve behavioral neurophysiology experiments, particularly in mice.