Breathing Process Research Articles

Node-Position-Based Joint Relay Selection and Adaptive Power Control Scheme in Wireless Body Area Networks

Sport and healthcare monitoring have become more and more popular in our everyday life, benefiting from the deploying of Wireless Body Area Networks. In these cases, data transmission reliability should be studied to receive the accurate real-time feedbacks, which contain rich biomedical information, such as heartbeat, and breathing process. However, wireless on-body channels experience significant temporal variation due to body movements and single-hop communication scheme cannot adapt to highly dynamic network topology. In this paper, a joint relay selection and power control scheme (JRP) is proposed to improve transmission reliability. We take running activity for experimental study, the influence of nodes’ positions to radio performance is evaluated. By analyzing the source and destination, JRP can decide the way to finish this communication by either relay selection or power control. In addition, the acceleration of each node is measured by accelerometers. Thus, with the help of real-time received signal strength indication and acceleration, JRP can pick several potential relay nodes for the source node’s transmission request. Finally, the experimental result shows that our scheme can achieve a good tradeoff between reliability and energy consumption.

Análise histológica das brí­¢nquias e do fí­­gado de Bryconops caudomaculatus em diferentes concentrações de amônia

O objetivo foi avaliar os efeitos de diferentes concentrações de amônia não ionizada (zero; 0,15; 0,30; 0,50; 1,00 mg L-1 NH3) na histologia e morfologia das brí­¢nquias e fí­­gado de juvenis de Bryconops caudomaculatus. Após 96 horas de exposição, os peixes foram anestesiados e submetidos í­Â necropsia para coleta de brí­¢nquias e fí­­gado, que foram incluí­­dos em parafina. Alterações morfológicas nas lamelas secundárias das brí­¢nquias foram observadas em concentrações a partir de 0,15 mg L-1, como hiperplasia, hipertrofia, deslocamento epitelial, fusão lamelar, edema, aneurisma lamelar com ruptura do epitélio e aumento na largura das lamelas. O fí­­gado apresentou alterações histológicas (congestão nos capilares, processos inflamatórios e pigmentação endógena) na presença de 0,30 mg L-1 de NH3, que comprometeram as funções vitais, o metabolismo, processos de respiração, desintoxicação do organismo, hematopoese e provavelmente a osmorregulação. Os resultados sugerem que as alterações nas brí­¢nquias e fí­­gado podem ser usadas para monitorar o desempenho de peixes em cultivo intensivo.

CFD Modelling of Flow Interaction in the Breathing Zone of a Virtual Thermal Manikin

The presented work partly reveals the development stage of a Virtual Thermal Manikin (VTM), equipped with additional breathing functionality. The methods used are based on Computational Fluid Dynamics (CFD) flow simulations and analysis. Real thermal manikins, as well as the VTMs, represent modern, highly complex tools for assessment of the occupants’ thermal comfort, as well as for analyses of indoor air quality in real or virtual enclosed environment. Also, real thermal manikins can be equipped with auxiliary devices that mimic human activities such as breathing, sweating, sneezing, coughing and others. Recent research indicates the development of an advanced compact pneumatic system, designed for implementation in the thermal manikin, capable of simulating the breathing related processes in humans. That is why the development of supplementary functionalities of the VTMs is considered as an important factor in the described research area. Thus, the presented case study reveals CFD based model of human body, with steady state breathing phases simulating the real human breathing processes. The results considering the flow interaction in the breathing zone showed good visual illustration and representation of the real physical processes.

Breathing as a Fundamental Rhythm of Brain Function.

Ongoing fluctuations of neuronal activity have long been considered intrinsic noise that introduces unavoidable and unwanted variability into neuronal processing, which the brain eliminates by averaging across population activity (Georgopoulos et al., 1986; Lee et al., 1988; Shadlen and Newsome, 1994; Maynard et al., 1999). It is now understood, that the seemingly random fluctuations of cortical activity form highly structured patterns, including oscillations at various frequencies, that modulate evoked neuronal responses (Arieli et al., 1996; Poulet and Petersen, 2008; He, 2013) and affect sensory perception (Linkenkaer-Hansen et al., 2004; Boly et al., 2007; Sadaghiani et al., 2009; Vinnik et al., 2012; Palva et al., 2013). Ongoing cortical activity is driven by proprioceptive and interoceptive inputs. In addition, it is partially intrinsically generated in which case it may be related to mental processes (Fox and Raichle, 2007; Deco et al., 2011). Here we argue that respiration, via multiple sensory pathways, contributes a rhythmic component to the ongoing cortical activity. We suggest that this rhythmic activity modulates the temporal organization of cortical neurodynamics, thereby linking higher cortical functions to the process of breathing.

How to Wire the Diaphragm: Wholemount Staining Methods to Analyze Mammalian Respiratory Innervation.

Direct or indirect impairment of breathing in humans by diseases or environmental factors can either cause long-term disability and pain, or can ultimately result in death. Automatic respiratory centers in the brainstem control the highly structured process of breathing and signal to a specialized group of motor neurons in the cervical spinal cord that constitute the phrenic nerves. In mammals, the thoracic diaphragm separates the thorax from the abdomen and adopts the function of the primary respiratory musculature. Faithful innervation by the phrenic nerves is a prerequisite for correct functionality of this highly specialized musculature and thus, ultimately, the viability of the entire organism.To analyze the effects of diseases and genetic defects responsible for deleterious or lethal respiratory phenotypes, accurate imaging of respiratory innervation during embryonic development, e.g., in genetically modified mouse models enables the characterization of specific marker genes and pathways that underlie appropriate wiring of the diaphragm. Among the different available immunostaining techniques, wholemount staining methods provide the advantage of clear and faithful three-dimensional information about the location of the antigens of interest. In comparison to routine histological techniques, however, the researcher has to deal with technical challenges, such as antibody penetration, the stability and availability of the antigen, and clearing of the relevant tissue, and the need to be equipped with state-of-the-art microscope equipment.In this methodological chapter, we explain and share our expertise concerning wholemount processing of mouse embryos and thoracic diaphragms for the analysis of mammalian respiratory innervation.

Control of 12-Cylinder Camless Engine with Neural Networks

The 12-cyliner camless engine breathing process is modeled with artificial neural networks (ANN’s). The inputs to the net are the intake valve lift (IVL) and intake valve closing timing (IVC) whereas the output of the net is the cylinder air charge (CAC). The ANN is trained with data collected from an engine simulation model which is based on thermodynamics principles and calibrated against real engine data. A method for adapting single-output feed-forward neural networks is proposed and applied to the camless engine ANN model. As a consequence the overall 12-cyliner camless engine feedback controller is upgraded and the necessary changes are implemented in order to contain the adaptive neural network with the objective of tracking the cylinder air charge (driver’s torque demand) while minimizing the pumping losses (increasing engine efficiency). All the needed measurements are extracted only from the two conventional and inexpensive sensors, namely, the mass air flow through the throttle body (MAF) and the intake manifold absolute pressure (MAP) sensors. The feedback controller’s capability is demonstrated through computer simulation.

Computational models of the neural control of breathing.

The ongoing process of breathing underlies the gas exchange essential for mammalian life. Each respiratory cycle ensues from the activity of rhythmic neural circuits in the brainstem, shaped by various modulatory signals, including mechanoreceptor feedback sensitive to lung inflation and chemoreceptor feedback dependent on gas composition in blood and tissues. This paper reviews a variety of computational models designed to reproduce experimental findings related to the neural control of breathing and generate predictions for future experimental testing. The review starts from the description of the core respiratory network in the brainstem, representing the central pattern generator (CPG) responsible for producing rhythmic respiratory activity, and progresses to encompass additional complexities needed to simulate different metabolic challenges, closed-loop feedback control including the lungs, and interactions between the respiratory and autonomic nervous systems. The integrated models considered in this review share a common framework including a distributed CPG core network responsible for generating the baseline three-phase pattern of rhythmic neural activity underlying normal breathing. WIREs Syst Biol Med 2017, 9:e1371. doi: 10.1002/wsbm.1371 For further resources related to this article, please visit the WIREs website.

Analyzing Breathing Signals and Swallow Sequence Locality for Solid Food Intake Monitoring.

Self-reported questionnaires are widely used by researchers for analyzing the dietary behavior of overweight and obese individuals. It has been established that questionnaire-based data collection often suffers from high errors due to its reporting subjectivity. Automatic swallow detection, as an alternative to questionnaires, is proposed in this paper to avoid such subjectivity. Existing approaches for swallow detection include the use of surface electromyography and sound to detect individual swallowing events. Many of these methods are generally too complicated and cumbersome for daily usage in a free-living setting. This paper presents a wearable solid food intake monitoring system that analyzes human breathing signals and swallow sequence locality. Food intake is identified by detecting swallow events. The system works based on a key observation that the otherwise continuous breathing process is interrupted by a short apnea during swallowing. A support vector machine (SVM) is first used for detecting such apneas in breathing signals collected from a wearable chest belt. The resulting swallow detection is then refined using a hidden Markov model (HMM)-based mechanism that leverages the known temporal locality in the sequence of human swallows. Temporal locality is based on the fact that people usually do not swallow in consecutive breathing cycles. The HMM model is used to model such temporal locality in order to refine the SVM results. Experiments were carried out on six healthy subjects wearing the proposed system. The proposed SVM method achieved up to 61% precision and 91% recall on average. Utilization of HMM in addition to SVM improved the overall performance to up to 75% precision and 86% recall.

A framework for modelling the biomechanical behaviour of the human liver during breathing in real time using machine learning

Progress in biomechanical modelling of human soft tissue is the basis for the development of new clinical applications capable of improving the diagnosis and treatment of some diseases (e.g. cancer), as well as the surgical planning and guidance of some interventions. The finite element method (FEM) is one of the most popular techniques used to predict the deformation of the human soft tissue due to its high accuracy. However, FEM has an associated high computational cost, which makes it difficult its integration in real-time computer-aided surgery systems. An alternative for simulating the mechanical behaviour of human organs in real time comes from the use of machine learning (ML) techniques, which are much faster than FEM. This paper assesses the feasibility of ML methods for modelling the biomechanical behaviour of the human liver during the breathing process, which is crucial for guiding surgeons during interventions where it is critical to track this deformation (e.g. some specific kind of biopsies) or for the accurate application of radiotherapy dose to liver tumours. For this purpose, different ML regression models were investigated, including three tree-based methods (decision trees, random forests and extremely randomised trees) and other two simpler regression techniques (dummy model and linear regression). In order to build and validate the ML models, a labelled data set was constructed from modelling the deformation of eight ex-vivo human livers using FEM. The best prediction performance was obtained using extremely randomised trees, with a mean error of 0.07 mm and all the samples with an error under 1 mm. The achieved results lay the foundation for the future development of some real-time software capable of simulating the human liver deformation during the breathing process during clinical interventions.

Human exhalation characterization with the aid of schlieren imaging technique

The purpose of this paper is to determine the dispersion and distribution characteristics of exhaled airflow for accurate prediction of disease transmission. The development of airflow dynamics of human exhalation was characterized using nonhazardous schlieren photography technique, providing a visualization and quantification of turbulent exhaled airflow from 18 healthy human subjects whilst standing and lying. The flow shape of each breathing pattern was characterized by two angles and averaged values of 18 subjects. Two exhaled air velocities, um and up, were measured and compared. The mean peak centerline velocity, um was found to decay correspondingly with increasing horizontal distance x in a form of power function. The mean propagation velocity, up was found to correlate with physiological parameters of human subjects. This was always lower than um at the mouth/nose opening, due to a vortex like airflow in front of a single exhalation cycle. When examining the talking and breathing process between two persons, the potential infectious risk was found to depend on their breathing patterns and spatial distribution of their exhaled air. Our study when combined with information on generation and distributions of pathogens could provide a prediction method and control strategy to minimize infection risk between persons in indoor environments.

Conspiring with Keats: Toward a Poetics of Breathing

ABSTRACTThis essay argues that Keats understood poetic performance as a conspiring, a powerfully somatic, often eroticized communion of poet and reader he figured as a process of mutual breathing. Owing to his personal history and medical expertise, Keats’s attitude toward respiration was deeply ambivalent: if a precipitant of death, breathing – the rhythmic conspiring through which poetic forms materialized in the bodies of readers during utterance – could be curative, even afford the poet a secular, aesthetic version of immortality. His embodied, breath-centered concept of reading and writing depended on a psychosomatic model of cognition that grounded intellectual activity in the life of the sensorium.

Research on drag reduction performance of turbulent boundary layer on bionic jet surface

Based on the fact that jet formed in outer gill of sharks can reduce the wall friction during the breath process, a bionic jet surface model was established. The numerical simulations were carried out using shear stress transport k−ω model, and the simulation results accorded with that of experiments. First, in the case of fixed flow-velocity ratio, the drag reduction performance would be better with the smaller jet’s angle, and the impact that the angle has on the drag reduction would be greater with the increase in jet hole’s aperture. Second, in the case of fixed jet’s angle, the drag reduction had a nearly linear relationship with flow–velocity ratio. Namely, the drag reduction would be better as the flow–velocity ratio increased, and the larger the jet hole’s aperture, the better the drag reduction. In addition, compared with the case of smoothing surface, the flow structure in turbulent boundary layer was changed by jet, increasing the thickness of viscous bottom layer and decreasing the gradient of normal velocity perpendicular to wall. Finally, the drag reduction mechanism was proposed based on the increased velocity effect of turbulent core, isolation effect of wall and the increased turbulent damping effect.

Effect of glottic geometry on breathing: three-dimensional unsteady numerical simulation of respiration in a case with congenital glottic web.

Glottic obstruction is a major cause of dyspnea. Without understanding the normal function of the glottis in breathing, treating dyspnea does not restore normal physiology. Therefore, we designed a computational fluid dynamics (CFD) model that tested the respiratory cycle in larynges with normal glottis and congenital glottic web (CGW). A CGW case and a control subject (CC) were selected from the computed tomography (CT) archive. 3D computational models of the larynges with structured boundary layer were constructed from axial CT images after mesh refinement study. CFD analyses were based on the Reynolds-averaged Navier-Stokes approach. Incompressible flow solver (pressure-based) and SST k-w turbulence model were chosen for this study. To simulate a real-time breathing process, time varying flow rate boundary condition was derived from the spirometer of a healthy, non-smoking woman. Glottic areas were measured as 51.64 and 125.43mm(2) for the CGW patient and CC, respectively. Time-dependent velocity contours and streamlines for the CC and CGW patient were drawn. The CC showed uniform flow, all through the inspiration and expiration phases. However, the CGW patient showed separation of flow at the glottis level, which caused areas of stagnation in the supraglottis (during expiration) and the subglottis and trachea (during inspiration). Specialized geometry of the normal larynx maintained uniform flow with low shear stress values on the wall even at high mass flow rates. Distortion of this geometry may cause obstruction of flow at multiple levels and, therefore, should be evaluated at multiple levels.

NUMERICAL ANALYSIS OF FLOW CHARACTERISTICS FOR THE NORMAL HUMAN UPPER AIRWAY

Based on the data from the spiral Computerized Tomography (CT) images, three dimensional models consisting of the airway from nasal cavity, pharynx and trachea to triple bifurcation are built. Computational fluid dynamics (CFD) method is applied to study the respiratory air flow dynamics within the upper respiratory tract of human body. The influence of different respiratory routes on airway resistance and within the respiratory air flow characteristics is studied under the respiration of the nose and mouth. The influence of the different respiratory route on the characteristics of airflow and the airway resistance were studied at the work of nasal and oral. When only a small amount of air flow is inhaled and exhaled through the oral, the distribution law of airflow in the airways is similar to that of breathing process only through the nose. With the increase of mouth breathing air flow rate, the airway of the highest airflow velocity and the total pressure drop are reduced. Except for the nasal cavity, where the airway resistance was decreased, the airway resistance of other parts was increased with increasing mouth breathing. When the airflow exchanged with the outside world mainly through mouth, the distribution of airflow in the airways were obviously different, especially in the nose, mouth and throat, which brought the new allocation of the airway resistance and the great reduction of nasal resistance. The airway resistance mainly concentrated in the oral cavity and the following airway. The results of numerical simulation are useful for studying the pathogenesis and diagnosing the diseases related to the anatomical structure and function of upper airway.

CO2-breathing and piercing polymersomes as tunable and reversible nanocarriers.

Despite numerous studies on utilizing polymeric vesicles as nanocapsules, fabrication of tunable molecular pathways on transportable vesicle walls remains challenging. Traditional methods for building penetrated channels on vesicular membrane surface often involve regulating the solvent polarity or photo-cross-linking. Herein, we developed a neat, green approach of stimulation by using CO2 gas as “molecular drill” to pierce macroporous structures on the membrane of polymersomes. By simply introducing CO2/N2 gases into the aqueous solution of self-assemblies without accumulating any byproducts, we observed two processes of polymeric shape transformation: “gas breathing” and “gas piercing.” Moreover, the pathways in terms of dimension and time were found to be adjustable simply by controlling the CO2 stimulation level for different functional encapsulated molecules in accumulation, transport, and releasing. CO2-breathing and piercing of polymersomes offers a promising functionality to tune nanocapsules for encapsulating and releasing fluorescent dyes and bioactive molecules in living systems and also a unique platform to mimic the structural formation of nucleus pore complex and the breathing process in human beings and animals.

Development of a Finite Element Model for Lung Tumor Displacements During Breathing

During clinical procedures for investigations of lung tumors, such as bronchoscopy, the breathing process causes movement of tumor nodules, affecting thus the accuracy of the determinations. In order to reduce the excessive irradiation during medical imaging procedures used by clinicians to track the tumor movements, biomechanical models of the respiration process based on the finite element method are currently being developed. This paper describes a methodology for obtaining a finite element model used to assess the magnitude of displacements inside the lungs during the breathing process. A simple to apply method of imposing lung outer surface boundary conditions is developed using an algorithm implemented in MATLAB. The influence of the mesh size on the accuracy of the resulted outer surface displacements was checked by simulating the same conditions for a spherical object.

A breathing MOF: direct crystallographic observation of the site-selective C(sp3)–H functionalization

A 3D breathing MOF was synthesized for light-driven acceleration of the site-selective C(sp3)–H activation. The 1D channels of the assembled MOF can encapsulate reaction substrates via a breathing process that were observed by single-crystal X-ray analyses.

Influence of a breathing process on the perception of the thermal environment using personalised ventilation

This paper presents the findings of a study examining the influence of the breathing process on the perception of the thermal environment during the use of personalised ventilation (PV). The measurements were made on a sitting thermal manikin with various options of air terminal device, ambient temperature and PV air supply. The thermal environment was assessed by means of the equivalent temperatures measured for each segment of the thermal manikin. The values of teq were calculated for the variants of the breathing function being switched on or off. Based on the measurement results, the values of equivalent temperature were determined to be lower for a breathing variant than for a non-breathing variant, irrespective of whether the PV system was used to heat or to cool. Therefore, the results confirmed that breathing air jets have the potential to influence the users' thermal sensation. This information is particularly important for the design of the ventilation and air conditioning systems that affect the parameters of the environment in the vicinity of human body.

The ability of people with intellectual disability to use inhalers – an exploratory mixed methods study

Objective: This aim of this study was to assess inhaler technique of people with intellectual disability (ID), and evaluate the effectiveness of teaching with respect to their individual ability to adopt correct technique. Methods: Seventeen people with ID were recruited through existing networks of general practitioners and disability support organisations. Inhaler technique was assessed using validated checklists and placebo devices, followed by provision of individualised training. The educational interaction between participant and researcher was captured via video recording and analysed qualitatively. Results: Seventeen people with ID participated; females comprised 65%. At baseline, no participants correctly used any device. Pressurised metered dose inhalers, with or without accessory devices, were the most poorly used devices. Inhalation steps were poorly performed across all devices. Following training, the proportions of assessed participants that were able to master inhaler technique were 100% of Accuhaler users, 40% of Turbuhaler users, 25% of pressurised metered dose inhaler users and 0% of Handihaler users. Barriers identified included poor comprehension of breathing processes, the lack of attentiveness and poor dexterity. Facilitators for educator delivery of inhaler technique education included the use of analogies and being patient. Conclusions: This is the first study to examine inhaler technique mastery in people with ID. Results show that with education that addresses the unique patient barriers inherent in this group, some individuals can be trained to mastery. Structured modules of inhaler technique training tailored for people with ID, but which can be individualised, are recommended.

Matlab Simulink Simulation of Respiratory Effort Energy Harvester Using Electromagnetic Generator

Electromagnetic generator as respiratory effort energy harvester is designed as a renewable energy source to generate a low power and exploiting human motion to extract energy. By selecting respiratory effort as energy harvester it can be carried out 24 hours as long as the electromagnetic generator is wearing on the human chest. It is because the electromagnetic generator functions when there is a motion of the chest wall. The electromagnetic generator basically constructed with two miniature dc motor generator, pulley, belt, gear and chest belt. The generator operates when there is change in chest wall circumstance during exhalation breathing process. The low power that produces can be apply on low power devices such as sensor or microcontroller. Simulation is done using Matlab Simulink to verify that respiratory effort able to produce the minimum required power to power up low power devices. Result from the simulation showing good outcome with 2.5mW of output power.