Peak Airflow Research Articles

Aerodynamic Study of Velopharyngeal Insufficiency in 22q11.2 Deletion Syndrome.

We aim to verify velopharyngeal sphincter function in 22q11.2 deletion syndrome patients (22q11.2DS) to establish correlations between aerodynamic and perceptual measures of nasality, and to identify aerodynamic measures differentiating typical from atypical velopharyngeal behavior. Eleven subjects with 22q11.2DS and twenty similar-age control subjects were recruited. The aerodynamic measures were mean Sound Pressure Level, air pressure peak, pressure wave duration, airflow pattern and nasal airflow during the sequence /pi/. The nasality perceptual measures were rhinolalia, rhinophony and nasal air escape. Airflow patterns and perceptual measures were statistically different in the two groups. Pressure wave duration and air pressure peak were lower in study subjects than in controls. Air pressure peak and nasal airflow were negatively correlated with rhinolalia; pressure wave duration was negatively correlated with nasal air escape and rhinolalia in 22q11.2DS patients. This aerodynamic study identified velopharyngeal qualitative and quantitative dysfunctions, suggesting heterogeneous models of velopharyngeal function in syndromic subjects as compared to controls.

Study of the Static Characteristics of Gas-Lubricated Thrust Bearings Using Analytical and Finite Element Methods

A study was conducted to develop a porous aerostatic rectangular thrust bearing model, with the aim of assessing how different operational conditions and geometric factors influence its static capabilities. Initially, the Reynolds equation was analytically solved. Subsequently, simulations were performed on the rectangular air bearing model. Analyzing the impact of throttle hole configurations, air film thickness, orifice size, and supply pressure revealed their significant effect on the bearing’s load capacity, air consumption, peak airflow speed in the air film gap, and rigidity. Experimental validations were further conducted on manufactured bearings, corroborating the theoretical findings. It was observed that extending the length of the rectangular throttle hole array progressively increases gas consumption and diminishes stability, while the load capacity and stiffness initially surge then taper off. A thinner air film enhances load capacity and reduces gas flow, contributing to increased stability. Conversely, enlarging the orifice diameter boosts both load capacity and stability but escalates mass flow and diminishes stiffness. Elevating gas supply pressure enhances load capacity, flow rate, and stiffness, albeit at the cost of reduced stability. A comparative analysis among experimental data, finite element analysis, and analytical solutions showed strong congruence, affirming the precision of the latter two methods for predicting the bearing’s performance. This investigation aids with refining bearing design for precision devices and offers insights to enhance bearing efficiency and lifespan and to reduce friction and wear. Given its lower computational demands, the analytical approach provides a rapid means to assess static characteristics, underscoring its utility alongside finite element techniques for optimizing aerostatic bearing parameters.

External photoglottography, intra-oral air pressure, airflow and acoustic data on the Korean fricatives /s’, s/

From simultaneous recordings of the external photoglottography, intra-oral air pressure (P_io), airflow and acoustic data from four native Seoul Korean speakers (2 male and 2 female), we have found that the two fricatives are not significantly different in glottal opening peak and airflow peak height either word-initially or word-medially and that the duration of aspiration is significantly reduced in word-medial /s/, compared to those in word-initial /s/, not in /s’/. We have also found that the duration of a high P_io plateau is significantly longer in /s/ than in /s’/ both word-initially and word-medially and that airflow resistance (R=P_io/U) at the onset and offset of a P_io plateau and at the time of airflow peak height is significantly higher in /s’/ than in /s/ across the contexts. However, the differences in P_io peak and F0 are not significant. In addition, the transition time to reach airflow peak height from the offset of a P_io plateau is found to be significantly longer in /s/ than /s’/ in both word-initial and word-medial positions. No significant differences in glottal opening peak and airflow peak height confirm that /s/ is specified as [–spread glottis] like /s’/. As for the other significant differences, we propose that /s/ is [–tense], and /s’/ [+tense].

Effect of different anesthetic dose of pentobarbital on respiratory activity in rabbits

Anesthetics inhibit the respiratory muscles and even cause upper airway to collapse. Diaphragm electromyography (EMGdi) and airflow signals are usually extracted to assess the degree of respiration inhibition by anesthetics. However, the ECG interference in EMGdi affects the accuracy of its time domain and frequency domain information extraction. We studied the changes in EMGdi (left EMGdi and right EMGdi) and airflow characteristics under two pentobarbital anesthetic doses. First, we filtered out the ECG in EMGdi based on the combination of stationary wavelet transform and the positioning of ECG to obtain EMGdi without ECG interference (EMGdip). The effectiveness of filtering algorithm was verified by calculating the power spectrum before and after noise reduction. Second, root mean square (RMS), average rectified value (ARV), and fixed sample entropy (fSampEn) were used to quantify EMGdi (left EMGdi, left EMGdip and right EMGdi). Median frequency (MF) and centroid frequency (fc) of EMGdi were calculated. Tidal volume, respiratory cycle duration and peak airflow were calculated from airflow. Finally, the average and standard deviation of these parameters for all rabbits (n = 10) were compared and analyzed under two anesthesia states. Our results indicate that anesthesia induced by an increase in pentobarbital dose leads to decrease in ventilation and EMGdi amplitude. There was no significant change in diaphragm power spectrum (MF and fc) with the increase of anesthesia dose.

Dynamic alpha factors: Prediction in time and evolution along reactors

The performance of aeration – one of the most costly processes at water resource recovery facilities – is heavily impacted by actual wastewater characteristics which are commonly taken into account using the alpha factor (α). This factor varies depending on hydraulic and organic loading; such variance includes both time and spatial fluctuations. In standard design practice, it is often considered as a fixed number, or at best, a predefined time series. The objective of this paper is to propose a new method of predicting plantwide trends in the α factor through the use of process modelling which can accommodate diurnal and seasonal variations. The authors’ concept takes into account the dependence of α on sludge retention time in the form of degradation kinetics, the effects of organic loading (influent filtered COD), the presence or absence of anoxic zones, diffuser depth, and the impact of high MLSS found in certain, e.g., MBR, technologies. The developed model was calibrated using data from numerous facilities, relying on off-gas measurements and tests in clean and process water. Model validation was carried out against averaged α factor gradient data from one plant, and against diurnal air flow measurements from another. The Benchmark Simulation Model 1 configuration was used to demonstrate the applicability of the proposed model – in estimation of blower energy consumption and peak air flow requirements – comparing it with constant and scheduled α factor-based approaches.

Acoustic and aerodynamic aspects of nasality in Guarani

Guarani presents some interesting characteristics for nasality: nasalization of voiceless and voiced fricatives and long nasal spans in which two types of nasals (strong and weak) are observed. This study is based on recordings made with 4 native Guarani speakers from Paraguay (1 woman and 3 men) using synchronized acoustic and aerodynamic (oral and nasal airflow) recordings. Data show that voiced fricatives lose their frication when nasalized ṽ > ʋ̃ [1]. For voiceless fricatives some nasal airflow can be observed, but no acoustic effects are observed below a certain threshold. Above this threshold, the acoustic spectrum is damped and the frication noise intensity is reduced, creating acoustically predictable phonetic variants s̃ > θ; x̃ > h. Thus, perceptually oral segments can be produced with a velopharyngeal port opening during voiceless fricatives, letting weak nasal airflow passing through (0.1–0.2 dm3/s). Two types of nasals are observed in nasal spans: strong and weak [2]. Strong nasals occurring after voiceless obstruents have a sharp nasal airflow peak, up to 2 dm3/s, after the oral constriction. This shows that the velum closure is achieved after the oral closure. Weak nasals occur in the environment of sonorants and vowels with weaker nasal airflow values. [1] J. J. Ohala and M. Ohala (1993). [2] E. Gregores and J. A. Suarez (1967).

Effects of Osteopathic Manipulation and Other Manual Manipulative Treatments on Cystic Fibrosis

Abstract Context: Cystic fibrosis (CF) is a genetic disease that affects multiple organ systems, and symptoms include chronic cough, gastrointestinal (GI) malabsorption, exercise intolerance, and chronic pain. Examples of standard treatments are nebulizers, supplementary enzymes, chest percussive therapy, respiratory therapy, and lifestyle modifications. Objective: The purpose of the current review was to determine whether manual therapies, such as osteopathic manipulative treatment (OMT), in conjunction with standard treatments, provide symptom relief for patients with CF. Methods: PubMed was searched to identify studies investigating the role of manual medicine in the care of CF patients. Search terms included chiropractic, physical therapy, physiotherapy, osteopathic, manipulation, massage, and manual medicine. All terms were searched in combination with cystic fibrosis. Studies investigating only exercise or chest percussive therapy as adjunctive treatments were excluded. Results: Eight studies were found that investigated manual therapies alone or in conjunction with exercise for treatment of CF symptoms. All studies reported improvement after manual therapy in 1 or more symptoms, such as posture, GI symptoms, peak airflow, anxiety, back or chest pain, or breathing. Study types included a case study, prospective observational studies, and randomized controlled trials. Most studies were small and statistically underpowered. In an inpatient/outpatient observational study of adults with CF, patients reported a significant reduction in pain after a single physiotherapy treatment, and inpatients also reported significantly improved breathing after treatment. In a randomized controlled trial involving adult CF outpatients, there was a significant improvement in chest and back pain scores between the OMT and control groups. Conclusions: Results of the current review suggested patients with CF can experience symptom relief after OMT and similar manual therapies. Patients subjectively reported improvement with manual therapies, and studies found statistically significant decreases in pain after a single treatment. However, larger studies with sufficient statistical power are needed to further define the role of manual therapies as adjunctive treatment for symptom relief in CF patients.

Comparison of disc and wire electrodes to restore cough via lower thoracic spinal cord stimulation

Objective To compare the safety and effectiveness of wire (WE) vs. disc (DE) electrodes to restore cough in subjects with spinal cord injury (SCI). Design Clinical trials assessing the effectiveness and clinical outcomes associated with two electrode systems to activate the expiratory muscles. Setting Inpatient hospital setting for DE or WE electrode insertion; outpatient evaluation of cough efficacy and instructions for home use. Participants Twenty-nine subjects with SCI; 17 participants with DE and 12 with WE implants. Intervention Surgical implantation of WE or DE to restore cough. Daily application of spinal cord stimulation (SCS) at home. Main outcome measure(s) Airway pressure (P) and peak airflow (F) generation achieved with SCS; clinical parameters including ease in raising secretions, incidence of acute respiratory tract infections (RTI) and side effects. Results P and F achieved with DE and WE were not significantly different. For example, at total lung capacity (TLC) with participant effort, P was 128 ± 12 cmH2O and 118 ± 14 cmH2O, with DE and WE, respectively. The degree of difficulty in raising secretions improved markedly in both groups. The incidence of RTI per year fell from 1.3 ± 0.3 and 1.3 ± 0.5–0.3 ± 0.1 and 0.1 ± 0.1 for DE and WE groups, respectively (P < 0.01 for both when compared to pre-implant values and NS between DE and WE groups). The only significant side effect i.e. short-term autonomic dysreflexia was also similar between groups. Conclusions The results of this investigation indicate that both DE and WE result in comparable degrees of expiratory muscle activation, clinical benefits and side effects. Importantly, SCS to restore cough can be achieved with use of WE which can be placed using minimally invasive techniques and associated reduction in cost, surgical time and overall risk. Trial registration: ClinicalTrials.gov identifier: NCT00116337., NCT01659541, FDA IDE: G980267

Single and sequential voluntary cough in children with chronic spinal cord injury

We investigated the impact of spinal cord injury (SCI) on cough capacity in 10 children (Mean ± SD, age 8 ± 4 years) and compared it to 15 typically developing children (age 8 ± 3 years). Participants underwent spirometry, single and sequential cough assessment with surface-electromyography from respiratory muscles. Inspiratory phase duration, inspiratory phase peak flow, inspiratory phase rise time, compression phase duration, expiratory phase rise time, expiratory phase peak airflow (EPPF) and cough volume acceleration (CVA) parameters of single and sequential cough were measured. Root mean square (RMS) values of right pectoralis-major, intercostal, rectus-abdominus (RA), and oblique (OB) muscles were calculated and mean of three trials were compared. The significance criterion was set at P < 0.05. The SCI group produced significantly lower lung volumes, EPPF, CVA, and RMS values of RA and OB during expiratory phases of single and sequential coughs. The decrease in activation in expiratory muscles in the SCI group accounts for the impaired expiratory flow and may contribute to risk of respiratory complications.

The Relationship Between Functional Decline of Care Recipients and Health of Caregivers

Pearlin’s stress-process model (2010) depicts that functional decline in care-recipient would shape caregiving burden and impact on caregiver’s health. With this background, we explored how the changes in care-recipients’ physical and cognitive functioning are related to the caregivers’ physical health. A total of 853 care-recipients from the Rounds 1 and 5 of the National Health and Aging Trend Study (NHATS) and their 1,303 caregivers from Round 5 of National Study of Caregiving (NSOC) were included. Multiple regression analyses were conducted to identify correlates of self-rated health and the number of chronic conditions with the change in physical and cognitive functioning from Round 1 to 5 and multidimensional caregiver burden. Physical functioning measured by the NHATS short physical performance battery included balance stands, walking chair stands, grip strength, and peak airflow. Memory, orientation, and executive functioning measured cognitive functioning. Multidimensional caregiver burden includes four domains (emotional, psychological, relationship, and resilience) identified with factor analysis. Background factors (recipient’s age, assisting recipients for 5 years, race/ethnicity, and number of chronic conditions of recipient) were included as covariates. After controlling covariates, the data showed that 5-year change of physical functioning and caregiver’s emotional burden were negatively significant for self-rated health; and assisting care-recipients for 5 years or more was significant for more numbers of chronic conditions among caregivers. Findings highlight that caregivers’ physical health is closely associated with care-recipient’s functional decline for long-term caregiving experiences. Further investigation on caregiver’s physical health using multiple health outcomes is needed to promote physical health in long-term caregivers.

CYCLOOXYGENASE MECHANISMS IN THE REGULATION OF RESPIRATORY EFFECTS OF TUMOR NECROSIS FACTOR

Introduction. It is known that the systemic level of the major pro-inflammatory cytokine increases in many respiratory diseases such as asthma, COPD and sleep apnea [1, 2]. The lung ventilation changes and the pathological types of breathing are typical in these diseases. By the reason, the research of the respiratory effects of cytokine is actual. The aim of this study was to compare the respiratory effects of tumor necrosis factor - α (TNF-α) before and after pretreatment with diclofenac, a nonspecific cyclooxygenase (COX) inhibitor. Materials and methods. Тhe experiments were performed in tracheostomized anaesthetized with urethane rats. A respiratory flow head connected to a pneumotachometer (AD Instruments ML141 Spirometer, Dunedin, New Zealand) was used to measure peak airflow and respiratory rate. The hypoxic ventilatory response was measured by using rebreathing with hypoxic gas mixture before and after the tail vein injection of TNF-α (10 μg/rat). In order to determine the role of the cyclooxygenase pathway in the ventilatory effects of TNF-α, introperitoneal administration of diclofenac, a nonspecific COX inhibitor, was used (0.5 mg/rat). Results and discussion. We have shown that the increase in level of TNF-α in blood increased the parameters of respiration such as minute ventilation (by 40%), tidal volume (by 18%), and the mean inspiratory flow (by 33%). The slope of the hypoxic ventilatory response decreased from 6.06 ± 0.91 to 3.48 ± 0.38 ml/min-1 mmHg-1 (by 40%) 40 min after administration of TNF-α (p &lt; 0.05), the slope of tidal volume and mean inspiratory flow also decreased (by 27%) (p &lt; 0.05). After pretreatment with diclofenac, the influence of TNF-α on breathing was dampened, as no significant changes were observed. Conclusion. We concluded that the elevation of inflammatory cytokine level in blood intensifies ventilation during the resting breathing that may be associated with increased central inspiratory activity. At the same time TNF-α reduces the chemoreflex sensitivity to hypoxia, thereby worsening the compensatory capabilities of the respiratory system. Thus, the results of our study suggest participation of inflammatory cytokines in mechanisms of central breathing control and chemoreception. Diclofenac pretreatment eliminated the respiratory effects of TNF-α. The data indicate that the ability of TNF-α to enhance basal ventilation and to reduce the ventilatory hypoxic response is mediated by the COX pathway.

Severe but not moderate hyperoxia of newborn mice causes an emphysematous lung phenotype in adulthood without persisting oxidative stress and inflammation

BackgroundPreterm newborns typically require supplemental oxygen but hyperoxic conditions also damage the premature lung. Oxygen-induced lung damages are mainly studied in newborn mouse models using oxygen concentrations above 75% and looking at short-term effects. Therefore, we aimed at the investigation of long-term effects and their dependency on different oxygen concentrations.MethodsNewborn mice were exposed to moderate vs. severe hyperoxic air conditions (50 vs. 75% O2) for 14 days followed by a longer period of normoxic conditions. Lung-related parameters were collected at an age of 60 or 120 days.ResultsSevere hyperoxia caused lower alveolar density, enlargement of parenchymal air spaces and fragmented elastic fibers as well as higher lung compliance with peak airflow limitations and higher sensitivity to ventilation-mediated damages in later life. However, these long-term lung structural and functional changes did not restrict the voluntary physical activity. Also, they were not accompanied by ongoing inflammatory processes, increased formation of reactive oxygen species (ROS) or altered expressions of antioxidant enzymes (superoxide dismutases, catalase) and lung elasticity-relevant proteins (elastin, pro-surfactant proteins) in adulthood. In contrast to severe hyperoxia, moderate hyperoxia was less lung damaging but also not free of long-term effects (higher lung compliance without peak airflow limitations, increased ROS formation).ConclusionsSevere but not moderate neonatal hyperoxia causes emphysematous lungs without persisting oxidative stress and inflammation in adulthood. As the existing fragmentation of the elastic fibers seems to play a pivotal role, it indicates the usefulness of elastin-protecting compounds in the reduction of long-term oxygen-related lung damages.

Impact of posterior septum resection on nasal airflow pattern and warming function

Background: The functional significance of the posterior segment of the septum is not fully understood.Aims/Objectives: The purpose of this study was to evaluate the impact of posterior septum resection with varying extents on nasal airflow pattern and warming function, and to determine the appropriate resection extent on posterior septum without disturbing airflow pattern.Material and Methods: Three dimensional models were established from the nasal CT scan of a healthy female volunteer without nasal disease. The models included the normal, as well as 1 cm, 2 cm, and 3 cm extent of posterior septum resection by virtual surgery. Using computational fluid dynamics, the airflow characteristics such as average and peak airflow velocity, average wall shear stress, average temperature and turbulence kinetic energy were recorded and compared among the four models.Results: By comparison with the normal model, the virtual surgeries with varying extents of posterior septum resection (1 cm, 2 cm, and 3 cm), demonstrated little alteration on indices of the average and peak airflow velocity, average wall shear stress, airflow temperature and turbulence kinetic energy. However, a statistical difference of the abovementioned indices existed when compared between varying planes of the nasal cavity (p < .001), although this did not appear to be significantly influenced by the degree of posterior septectomy.Conclusions and significance: From an aerodynamics perspective, little disturbance on airflow pattern and warming function of nasal cavity could be detected with increasing resection of posterior septum (up to 3 cm). These results may imply that resection of the posterior septum (up to 3 cm) has little impact on nasal function.

Event-triggered averaging of electrical impedance tomography (EIT) respiratory waveforms as compared to low-pass filtering for removal of cardiac related impedance changes.

Electrical impedance tomography (EIT) is used for bedside ventilation monitoring; cardiac related impedance changes represent a source of noise superimposed on the ventilation signal, commonly removed by low-pass filtering (LPF). We investigated if an alternative approach, based on an event-triggered averaging (ETA) process, is more effective at preserving the actual ventilation waveform. Ten paralyzed patients undergoing volume-controlled ventilation were studied; 30 breaths for each patient were identified to compare LPF and ETA. For ETA the identified breaths were temporally aligned on the beginning of inspiration; the values of the thirty curves at each time point were averaged. The analysis was conducted on the global EIT signal and on four ventral-to-dorsal regions of interest. Global tidal variations by ETA resulted higher than LPF (average difference 139 ± 88 arbitrary units, p = 0.004). Both for global and regional waveforms, minimum and maximum EIT slopes were steeper by ETA as compared to LPF (average difference respectively − 57 ± 60 mL/s and 144 ± 96 mL/s for global signal, p < 0.05); ventilator inspiratory peak airflow correlated with maximum slope measured by ETA (r = 0.902, p < 0.001), but not LPF (p = 0.319). Beginning of inspiration identified on the ventilator waveform and on the global EIT signal by ETA occurred simultaneously, (+ 0.04 ± 0.07 s, p = 0.081), while occurred earlier by LPF (− 0.26 ± 0.1 s, p < 0.001). Removal of cardiac related impedance changes by ETA results in a ventilation signal more similar to the waveforms recorded by the ventilator, particularly regarding the slope of impedance changes and time at the minimum values as compared to LPF.Electronic supplementary materialThe online version of this article (10.1007/s10877-019-00348-2) contains supplementary material, which is available to authorized users.

Impacts of moisture sources on the isotopic inverse altitude effect and amount of precipitation in the Hani Rice Terraces region of the Ailao Mountains

Generally, the isotopic composition of precipitation on the windward side of gigantic mountains has a negative altitude gradient. However, an inverse isotopic altitude effect occurs when there are diverse vapor sources. This paper takes the Quanfuzhuang River Basin (QRB), which lies in the Hani Rice Terraces region of the southern Ailao Mountains in southwest China, as the study area. The study analyzes the isotopic data of 42 precipitation samples collected between an elevation range from 1500 m to 2024 m a.s.l. during the rainy season (from May to October) of 2015. The results indicate that there is an inverse isotopic altitude effect of precipitation with a positive isotope altitude gradient of 0.47‰/100 m and 1.10‰/100 m for δ18O and δ2H, respectively, at the mountaintop, while the precipitation amount increases at related elevations. A mixture of over peak airflow and recycled vapor is responsible for the inverse altitude effect as well as increasing rainfall amount. The positive precipitation isotopic altitude gradient is primarily caused by the local water cycle, and the increased precipitation amount is mainly caused by over peak airflow. The inverse isotopic altitude effect is also found in the Colorado Rocky Mountains, the Central Hindu Kush Mountains and the Tianshan Mountains, and findings from those mountains support these findings on the influence of mixed moisture sources on isotopic inverse altitude effects.

Receptor for advanced glycation end-products modulates lung development and lung sensitivity to hyperoxic injury in newborn mice.

The receptor for advanced glycation end-products is mainly expressed in type I alveolar epithelial cells but its importance in lung development and response to neonatal hyperoxia is unclear. Therefore, our study aimed at the analysis of young wildtype and RAGE knockout mice which grew up under normoxic or hyperoxic air conditions for the first 14days followed by a longer period of normoxic conditions. Lung histology, expression of lung-specific proteins, and respiratory mechanics were analyzed when the mice reached an age of 2 or 4months. These analyses indicated less but larger and thicker alveoli in RAGE knockout mice, reverse differences in the mRNA and protein amount of pro-surfactant proteins (pro-SP-B, pro-SP-C) and aquaporin-5, and differences in the amount of elastin and CREB, a pro-survival transcription factor, as well as higher lung compliance. Despite this potential disadvantages, RAGE knockout lungs showed less long-term damages mediated by neonatal hyperoxia. In detail, the hyperoxia-mediated reduction in alveoli, enlargement of airspaces, fragmentation of elastic fibers, and increased lung compliance combined with reduced peak airflows was less pronounced in RAGE knockout mice. In conclusion, RAGE supports the alveolarization but makes the lung more susceptible to hyperoxic injury shortly after birth. Blocking RAGE function could still be a helpful tool in reducing hyperoxia-mediated lung pathologies during alveolarization.

Dose-dependent effects of mandibular advancement on upper airway collapsibility and muscle function in obstructive sleep apnea.

Mandibular advancement splints (MAS) are the leading treatment alternative to continuous positive airway pressure (CPAP) for obstructive sleep apnea (OSA). However, not all patients experience clinical benefit and treatment prediction remains challenging. Understanding the effects of mandibular advancement on pharyngeal collapsibility and muscle function may provide valuable information on the mechanisms of MAS, and thereby help to develop novel approaches for patient selection. Thus, we aimed to determine dose-dependent effects of mandibular advancement on pharyngeal collapsibility and muscle function concurrently in OSA patients undergoing MAS therapy. Twelve (11 male) MAS-naïve patients underwent a detailed physiology sleep study (polysomnography) to quantify pharyngeal collapsibility (PCRIT), pharyngeal muscle responsiveness to negative pharyngeal pressure (via genioglossus intramuscular electromyography and an epiglottic pressure sensor) and effectiveness to restore airflow and minute ventilation (Vi) after 1-minute transient CPAP reductions (induced airflow-limitation) at three mandibular advancement positions: 0% (habitual bite), 50% and 100% of the maximum comfortable mandibular advancement. Standard clinical polysomnography after MAS therapy optimization was performed to determine treatment outcome. Overall, participants were obese with severe OSA (mean ± SD: BMI = 31 ± 4 kg/m2, apnea-hypopnea index [AHI] = 33 ± 14 events/hour). PCRIT decreased with mandibular advancement in a dose-dependent manner (1.8 ± 3.9 vs. -0.9 ± 2.9 vs. -4.0 ± 3.6 cmH2O; p < 0.001). There was no systematic change in genioglossus muscle responsiveness (p = 0.09) or effectiveness to restore peak airflow (p = 0.4) or Vi (p = 0.7) with mandibular advancement. Mandibular advancement reduces pharyngeal collapsibility in a dose-dependent manner without systematically changing genioglossus muscle function in a predominantly obese and severe OSA population. This indicates that the primary mode of action of MAS therapy is via improvement in passive pharyngeal anatomy.

Investigations on Mandarin Aspiratory Animations Using an Airflow Model

Various three-dimensional (3-D) talking heads have been developed lately for language learning, with both external and internal articulatory movements being visualized to guide learning. Mandarin pronunciation animation is challenging due to its confusable stops and affricates with similar places of articulation. Until now, less attention has been paid to the biosignal information of aspiratory airflow, which is essential in distinguishing Mandarin consonants. This study fills a research gap by presenting the quantitative analyses of airflow, and then designing an airflow model for a 3-D pronunciation system. The airflow information was collected by Phonatory Aerodynamic System, so that confusable consonants in Mandarin could be discerned by mean airflow rate, peak airflow rate, airflow duration, and peak time. Based on the airflow parameters, an airflow model using the physical equation of fluid flow was proposed and solved, which was then combined and synchronized with the existing 3-D articulatory model. Therefore, the new multimodal system was implemented to synchronously exhibit the airflow motions and articulatory movements of uttering Mandarin syllables. Both an audio-visual perception test and a pronunciation training study were conducted to assess the effectiveness of our system. Perceptual results indicated that identification accuracy was improved for both native and nonnative groups with the help of airflow motions, while native perceivers exhibited higher accuracy due to long-term language experience. Moreover, our system helped Japanese learners of Mandarin enhance their production skills of Mandarin aspirated consonants, reflected by higher gain values of voice onset time after training.

The Mechanism and Representation of Korean Three-Way Phonation Contrast: External Photoglottography, Intra-Oral Air Pressure, Airflow, and Acoustic Data

This paper aims to refine our understanding of the speech mechanism and laryngeal features involved in the Korean lenis (/p t k/), aspirated (/ph th kh/), and fortis (/p' t' k'/) plosives. For this purpose we made measurements using a new noninvasive technique called external lighting and sensing photoglottography (ePGG) as well as intra-oral air pressure (Pio) above the glottis, airflow, and acoustic data. From simultaneous recordings of the experimental data, we were ableto quantify the laryngeal-oral coordination of glottal opening and a consonant release, and the covariance of airflow peak and duration of aspiration with glottal opening. The phasing of glottal opening and the 3-way phonation contrast occurs in the order, from early to late, fortis, lenis < aspirated plosives, and the glottal opening peak ranges from low to high in the same order. We also found that a Pio peak, the durations of a high Pio plateau and an oral closure, and F0 are independent of the glottal opening mechanism, varying in the order lenis < aspirated and fortis plosives. From these findings, we propose that the 2 independent patterns are accounted for by the articulator-based features [±spread glottis] and [±tense], respectively.

CFD simulation of airflow inside tree canopies discharged from air-assisted sprayers

Effective pesticide application is not only essential for specialty crop industries but also very important for addressing increasing concerns about environmental contamination caused by pesticide spray drift. Numerical analysis using computational fluid dynamics (CFD) can contribute to better understanding of the transport of spray droplets carried by strong air jets from sprayers. In this research, an integrated CFD model was developed to predict air velocity distributions inside and around tree canopies blown by an air-assisted pesticide sprayer. The sprayer motion was simulated by the sliding mesh technique, and the tree canopies were defined in the computational domain as virtual porous media without their geometric modeling. Validation of the CFD model was accomplished in three steps by comparing the CFD results with previous measurements. Air velocities and airflow pressures downwind from the sprayer agreed well with the measurements when the sprayer was both stationary and in motion. The model was also able to predict accurately the peak air velocity and airflow pressure inside the canopies with average RMS errors of 1.68ms−1 and 0.89kgm−2, and relative errors of 29.2% and 20.2%, respectively. Although discrepancy existed between the field experiment measurement and CFD simulation this study can conclude that the simulation will give a reasonable prediction of air distributions discharged from air-assisted sprayers. The validated CFD model was applied to predict air distribution inside canopies with various canopy dimensions and densities. The complex airflow patterns obtained by the CFD model offered advantages of analyzing effects of various factors on sprayer performance.