Determination of respiratory frequency from respiratory sinus arrhythmia

In the clinical setting, the observation of undisturbed spontaneous respiration and direct measurement of an "unbiased" respiratory rate is not a practical option. However, the respiratory modulation of the heart rate (respiratory sinus arrhythmia, RSA) offers a possibility of recording the respiratory rate indirectly. The present work introduces a novel procedure for extracting the respiratory rate from the ECG, and compares the results thus obtained with those of a previously applied method. The latter is based on the determination of dominant peaks in the amplitude spectrum of a five-minute RR interval time series. The new method presented here is based on the band pass filtering of a one-minute RR interval time series with subsequent analysis of the maxima, minima and zero crossings of the resulting RSA curve. The methods were compared by determining the respiratory rates of 16 healthy male subjects measured in 15 different experimental situations, including spontaneous and controlled breathing. The respiratory rate as determined by thermistor recording of nasal breath temperature was used as control. The mean deviation from directly measured respiratory rate was 2.9 min-1 for the new and 7.2 min-1 for the previous method. The new method proved superior under all conditions except controlled breathing at low frequencies. The present study thus demonstrates the high precision of respiratory rate determined indirectly by analysing the RSA curve. Since it requires no special instrumentation, this procedure is ideally suited for clinical application, and permits the continuous recording of respiratory rate over long periods of time.     

回转式螺旋气固换热装置内传热过程的数值模拟

采用自制回转窑换热装置对离心粒化后的高温炉渣颗粒进行余热回收,采用有限元分析软件及欧拉双流体模型对装置内气固两相流场进行数值模拟,研究进风风速及回转窑转速对气固换热效率的影响,并通过现场试验对模拟结果进行验证。结果表明,当回转体转速为16r/min、进风风速4.31 m/s时,颗粒的离散效果较好,热风温度达1 050K,此时的换热效果最好,数值模拟与试验结果高度吻合。     

内蒙古锡林河流域羊草草原植物生长旺季呼吸的影响因素分析和区分

Based on the static opaque chamber method, the respiration rates of soil microbial respiration, soil respiration, and ecosystem respiration were measured through continuous in-situ experiments during rapid growth season in semiarid Leymus chinensis steppe in the Xilin River Basin of lnner Mongolia, China. Soil temperature and moisture were the main factor affecting respiration rates. Soil temperature can explain most CO2 efflux variations (R2=0.376-0.655) excluding data of low soil water conditions. Soil moisture can also effectively explain most of the variations of soil and ecosystem respiration (R2=0.314-0.583), but it can not explain much of the variation of microbial respiration (R2=0.063). Low soil water content (≤5%) inhibited CO2 efflux though the soil temperature was high. Rewetting the soil after a long drought resulted in substantial increases in CO2 flux at high temperature. Bivariable models based on soil temperature at 5 cm depth and soil moisture at O-10 cm depth can explain about 70% of the variations of CO2 effluxes. The contribution of soil respiration to ecosystem respiration averaged 59.4%, ranging from 47.3% to 72.4%; the contribution of root respiration to soil respiration averaged 20.5%, ranging from 11.7% to 51.7%. The contribution of soil to ecosystem respiration was a little overestimated and root to soil respiration little underestimated because of the increased soil water content that occurred as a result of plant removal.     

Detection of respiratory events during NPSG: nasal cannula/pressure sensor versus thermistor

Recording of respiratory airflow is an integral part of polysomnography (NPSG). It is conventionally monitored with a thermistor that measures temperature as a surrogate of flow. The subjectivity of interpreting hypopnea from this signal has prompted us to measure nasal airflow directly with a simple pneumotachograph consisting of a standard nasal cannula connected to a 2-cm H2O pressure transducer. We manually analyzed respiratory events using simultaneous thermistor and nasal cannula in 11 patients with obstructive sleep apnea syndrome (OSAS) and 9 with upper airway resistance syndrome (UARS). Definite events were scored separately for each signal when amplitude was <50% for >10 seconds. Events were also scored on the nasal cannula signal when the flattened shape of the signal suggested flow limitation, and these were tabulated separately. Definite events in one signal were tabulated by whether the other signal showed a definite event or not. In addition, nasal cannula events were compared to a more liberal thermistor criterion (any change in the signal for > or = 2 breaths). Visually, events were more easily recognized on the nasal cannula signal than on the thermistor signal. In OSAS, 1,873 definite thermistor events were detected. Of these, 99.1% were detected by nasal cannula, and 0.9% were missed. Of 3,541 definite nasal cannula events, 51.9% were detected by definite thermistor criteria; 75.0% were detected by liberal thermistor criteria; 25.0% were missed. In UARS, 123 definite thermistor events were detected. Of these, 89.4% were detected by nasal cannula and 10.6% were missed. Nine hundred and three nasal cannula events were detected. However, only 17.2% of these were detected by definite thermistor criteria; 38.6% were detected by liberal thermistor criteria; 61.4% were completely undetected by thermistor. When events identified on the nasal cannula by flow limitation alone were excluded, the thermistor detected 30.1% of events by definite criteria and 78.6% by liberal criteria, still leaving 21.4% completely undetected by the thermistor. We conclude that the nasal cannula reliably detects respiratory events seen by thermistor. Additional events (including some characterized only by flow limitation) that help define the UARS, were recognized by nasal cannula but often completely missed by thermistor. We propose that respiratory monitoring during NPSG with nasal cannula significantly improves event detection and classification over that with thermistor.     

基于机器学习的北京市PM2.5浓度预测模型及模拟分析

对北京市周边8个点多个压力高度的温度、湿度和风速数据, 以及北京市PM2.5污染数据进行了分析和归一化处理, 建立了反向传播神经网络(back propagation, BP)、卷积神经网络(convolutional neural network, CNN) 和长短期记忆模型(long short-term memory, LSTM) 对上述气象数据和污染数据进行训练, 训练结果表明: 反向传播神经网络模型和卷积神经网络模型对未来1 h的PM2.5污染等级的预测准确率较低, 而长短期记忆模型的准确率较高.使用长短期记忆模型预测未来1 h的PM2.5污染值与实际值十分接近, 表明北京市的PM2.5污染与其周边地区的气象条件关系密切.通过利用长短期记忆模型对不同压力高度的气象数据进行训练和对比, 得出在利用气象数据预测污染时, 仅使用近地面气象数据比使用多个高度上的气象数据更加准确.      

Correction method for end-tidal xenon concentration in CBF measurements with xenon-enhanced CT

PURPOSE: The goal of this work is to show how variations in respiratory rate and tidal volume affect calculated cerebral blood flow (CBF) values on xenon-enhanced CT. In xenon-enhanced CT examination, the patient often takes shallow and rapid breaths. Thus, it is less likely that end-tidal xenon concentration reflects arterial xenon concentration, and appropriate correction measures should be taken for the end-distal respiratory data to obtain reliable CBF values. METHOD: Preliminary breathing tests were performed using a lung phantom to determine the influence of respiratory volume and rate on end-tidal xenon concentration. Two xenon-enhanced CT studies were conducted of a healthy person with completely different respiratory manners between two studies. One was deep and slow respiration. The other was shallow and rapid respiration. RESULTS: The lung phantom results prove that deep and slow respiration is essential for the end-tidal method. The results of xenon-enhanced CT studies of the same person show that the direct use of end-tidal data for shallow and rapid respiration leads to CBF values much lower than the actual values. CONCLUSION: Differences in respiratory rate and tidal volume during xenon inhalation can significantly affect calculated CBF values on xenon-enhanced CT. With use of the correction methods described herein, these effects can be minimized. We have derived the end-tidal correction method on the assumption that a person's CBF values should be kept unchanged regardless of different respiratory manners.     

Comparison of numerical modeling techniques for complex,two-dimensional,transient heat-conduction problems

The accuracy, stability, and cost of the standard finite-element method, (Standard), Matrix method method of Ohnaka, and alternating-direction, implicit finite-difference method (ADI) have been compared using analytical solutions for two problems approximating different stages in steel ingot processing. The Standard and Matrix methods both employ triangular elements and were compared using the Dupont, Lees, and Crank-Nicolson time-stepping techniques. Other variables include mesh and time-step refinement, type of boundary condition formulation, and the technique for simulating phase change. The best overall combination of methods investigated for modeling two-dimensional, transient, heat conduction problems involving irregular geometry was the Dupont-Matrix method with a lumped boundary condition formulation and temperature dependent properties evaluated at time level two, coupled with the Lemmon latent-heat evolution technique if phase change is involved. For problems with simple geometry, the ADI method was found to be more cost effective.     

The noninvasive demonstration of functional reinnervation after heart transplantation

Although RR interval variability appears to be an ideal method for assessing reinnervation after heart transplantation, it has been shown that respiratory sinus arrhythmia is caused by the mechanical effect of respiration on the right atrium. The neck-suction induces heart rate changes only by means of nervous reflex and its hemodynamic effect is local and hence appears as a useful method for assessing reinnervation. We tested the presence of autonomic reinnervation in 18 heart transplant recipients, compared to 12 donor-age-matched controls. We measured the power of RR interval low- (LF, around 0.1 Hz) and respiratory fluctuations (HF) before and during rhythmic neck-suction stimulation at 0.1 Hz and at a frequency (0.20 Hz) similar to, but distinct from, that of respiration (controlled at 0.25 Hz), before and during 0.04 mg/kg atropine infusion, using autoregressive spectral analysis of RR interval, respiration and neck pressure signals. The relationship between pairs of signals at each frequency was quantitatively assessed by bivariate coherence function. All transplanted subjects showed low-amplitude HF, related to respiration. Detectable LF (whose power was lower than in controls: 1.15 +/- 0.39 versus 6.08 +/- 0.27 1n-ms2, p < 0.001), non coherent with respiration, were present in 11/18 transplanted subjects, and correlated with months since transplantation (r = +0.59, p < 0.05). HF neck suction induced the presence of a 0.20 Hz fluctuation in 12/12 controls, distinct from and greater than the 0.25 Hz respiratory component (7.28 +/- 0.26 versus 6.69 +/- 0.74 1n-ms2, p < 0.01); this was not seen in any of the transplanted subjects.(ABSTRACT TRUNCATED AT 250 WORDS)     

烧结工艺对NiFe2O4-10NiO双相陶瓷烧结行为及微观结构的影响

采用粉末冶金法制备NiFe2O4-10NiO双相陶瓷,对该陶瓷在不同烧结气氛、不同烧结温度和保温时间等条件下的烧结行为进行研究,探讨烧结气氛、烧结温度和保温时间等对NiFe2O4-10NiO双相陶瓷烧结致密化进程及显微结构演变规律的影响.结果表明:N2气氛下NiFe2O4-10NiO双相陶瓷的致密化速率及晶粒长大速率均...     

制氧5#空分原料压缩机对中原则的确定

在很长一段时间里,因为没有找到控制空压机振动值的有效办法,5#空压机的运行一直处于不稳定状态.在寻找空压机振动规律及控制办法的过程中,发现空压机系统的三轴对中状态对振动的影响很大.进一步详细分析外方所提供的5#、6#空压机对中标准的计算过程,发现二者的差别在于对墙板的温差取值不同.为此,在不同环境温度下分别对5#、6#压缩机支撑墙板、增速箱箱体、混凝土基础的温度分布进行长期跟踪测量.根据测量的数据,从理论计算上初步确定了5#空压机组对中原则.在以后的检修中按上述确定的原则进行对中,其振动值长期稳定,说明上述对中原则与实际的对中值是吻合的.     

Electronic and magnetic stability in correlated transportations of rare-earth nickelate perovskites

Although the thermistor and metal to insulator transition bi-functionalities were discovered for rareearth nickelates(RENiO3),the electronic stability in their correlated transports under impulse voltage or magnetic field remain as open questions.Herein,we demonstrate the thermistor transportations of the electron correlated rare-earth nickelates under impulse direct current voltage and in magnetic environment.The insulating phase of RENiO3 shows zero crossing linear I-V characters,indicating their stable electronic resistance is independent of the imparted voltage up to 10 V and pulse width down to1 us,in spite of their sensitive electronic structures to polarizations.In addition,the high electronic stability associated with the thermistor transportation of RENiO3 is also demonstrated in magnetic fields up to 9 T(i.e.,MR<0.2%).The high electronic stability further paves the way to applying RENiO3 as a broad temperature range thermistor in temperature sensing or circuit protections for correlated electronics.     

A study of hepatic mitochondrial respiration and microsomal cytochrome P450 content in mice infected with the liver fluke Fasciola hepatica

Previous studies of the effects of infection of Wistar rats with the common liver fluke, Fasciola hepatica, on liver bioenergetic and drug metabolism have demonstrated a loss of respiratory control in isolated mitochondria and reduced microsomal cytochrome P450 content, respectively, from 2 weeks post-infection throughout the acute phase of the infection. In the present study male Balb/c mice infected with F. hepatica showed a loss of respiratory control in isolated liver mitochondria only at 4 weeks post-infection. A similar time course was demonstrated for a reduction in hepatic microsomal cytochrome P450 content. Preparations from infected CBA mice showed similar changes to Balb/c mice but mitochondrial respiration in preparations from infected Swiss outbred mice was normal. A host difference between strains of mice and between mice and rats is therefore evident in the timing and extent of liver mitochondrial dysfunction and in the timing of the decrease in the cytochrome P450 content of hepatic microsomes. This difference between hosts may be related to the reported differences in cellular inflammatory responses to the migrating juvenile flukes in the livers of rats and mice.     

Spectral analysis of an acoustic respiratory signal with a view to developing an apnoea monitor

The movement of air through the air passages during normal respiration generates an acoustic signal which can be detected from the surface of the body at suitable sites with the aid of a microphone applied to the skin. The spectral characteristics of these sounds were analysed to see if they could be differentiated from other sources of sound. During normal respiration the other major source of sound was that transmitted from the heart, and this could be filtered out with a band pass filter. A prototype apnoea monitor was built which utilised these sound signals as an indicator of respiration and underwent preliminary testing. Although such acoustic signals have the potential to indicate respiration, and cardiac sounds can be effectively filtered, further work would be required to recognise and reject other extraneous sources of sound interfering with the respiratory signal.     

Prediction of Velocity and Deformation Fields During Multipass Plate Hot Rolling by Novel Mixed Analytical-Numerical Method

 An integrated mathematical model is proposed to predict the velocity field and strain distribution during multi-pass plate hot rolling. This model is a part of the mixed analytical-numerical method (ANM) aiming at prediction of deformation variables, temperature and microstructure evolution for plate hot rolling. First a velocity field with undetermined coefficients is developed according to the principle of volume constancy and characteristics of metal flow during rolling, and then it is solved by minimizing the total energy consumption rate. Meanwhile a thermal model coupling with the plastic deformation is exploited through series function solution to determine temperature distribution and calculate the flow stress. After that, strain rate field is calculated through geometric equations and strain field is derived by means of difference method. This model is employed in simulation of an industrial seven-pass plate hot rolling process. The velocity field result and strain field result are in good agreement with that from FEM simulation. Furthermore, the rolling force and temperature agree well with the measured ones. The comparisons verify the validity of the presented method. The calculation of temperature, strain and strain rate are helpful in predicting microstructure. Above all, the greatest advantage of the presented method is the high efficiency, it only takes 12 s to simulate a seven-pass schedule, so it is more efficient than other numerical methods such as FEM.     

Hemodynamics, cerebral circulation, and oxygen saturation in Cheyne-Stokes respiration

Because cardiovascular disorders and stroke may induce Cheyne-Stokes respiration, our purpose was to study the interaction among cerebral activity, cerebral circulation, blood pressure, and blood gases during Cheyne-Stokes respiration. Ten patients with heart failure or a previous stroke were investigated during Cheyne-Stokes respiration with recordings of daytime polysomnography, cerebral blood flow velocity, intra-arterial blood pressure, and intra-arterial oxygen saturation with and without oxygen administration. There were simultaneous changes in wakefulness, cerebral blood flow velocity, and respiration with accompanying changes in blood pressure and heart rate approximately 10 s later. Cerebral blood flow velocity, blood pressure, and heart rate had a minimum occurrence in apnea and a maximum occurrence during hyperpnea. The apnea-induced oxygen desaturations were diminished during oxygen administration, but the hemodynamic alterations persisted. Oxygen desaturations were more severe and occurred earlier according to intra-arterial measurements than with finger oximetry. It is not possible to explain Cheyne-Stokes respiration by alterations in blood gases and circulatory time alone. Cheyne-Stokes respiration may be characterized as a state of phase-linked cyclic changes in cerebral, respiratory, and cardiovascular functions probably generated by variations in central nervous activity.     

霍戈文内燃式热风炉传输现象

利用CFD仿真对首钢1780 m³霍戈文内燃式热风炉进行了数值模拟分析,主要研究了空气和煤气混合前在矩形燃烧器中的流动,混合气体在燃烧室的燃烧、含量分布、温度分布、火焰形状以及拱顶的速度分布和温度分布.结果表明:空气喷嘴出口界面和煤气出口截面的流场都存在一定程度的不均匀性;沿燃烧室宽度方向,火焰高度变化剧烈;拱顶出口截面残余极少量的一氧化碳,蓄热室表面烟气速度分布不均,最高温差也很大.     

Mathematical Modeling of Lake Tap Flows

A lake tap is the submerged piercing of a tunnel at the intake to connect the reservoir to the tunnel system. It is referred to as a dry lake tap if the tunnel is dry before the blasting of the last rock plug at the tunnel entrance. Transient state conditions in the tunnel following a dry lake tap are modeled using the lumped and distributed-system approaches. Fourth-order Runge-Kutta method and the method of characteristics are used in the lumped-system model and distributed-system models, respectively. The results computed by the lumped and distributed-system approaches agree with one another. Pressures computed by using distributed-system and lumped-system models are compared with the experimental results available in literature for rapid filling of a pipeline with closed end. The rate of dissipation of pressure oscillations in the measured air pressure during prototype lake tap at Crater Lake Snettisham project in Alaska, and in the experiments reported in the literature is higher than that computed by the mathematical models using steady state friction and constant wave velocity.     

全柔性滑块机构的设计与分析

采用伪刚体模型法对全柔性滑块机构进行了变形分析,设计了一种微型全柔性滑块机构,并主要对其中的柔性移动副进行了设计与分析,给出了该设计实例柔性移动副的等效弹簧力,进而得到微型全柔性滑块机构伪刚体模型的分析结果.同时用有限元方法对该实例进行了仿真分析,两种方法所得结果基本一致,表明了理论分析是正确的,该实例的设计是可行的.     

The effect of a new tear substitute containing glycerol and hyaluronate on keratoconjunctivitis sicca

The present study of asthmatic children examined relationships among the frequencies of prior respiratory infections (i.e., those prior to the development of asthma) and recent (past year) respiratory infections, asthma severity, and the impacts of 12 common asthma triggers: air pollution, allergy problems, anger, cigarette smoke, excitement, high humidity, high or low environmental temperature, laughter, nighttime hours, physical activity, respiratory infection, and stress or worry. Data on these variables were obtained through a survey in which 325 families completed questionnaires; 121 families had asthmatic children who were 2-20 years of age. Pearson correlational analyses revealed many significant positive correlations: The frequencies of prior and recent infections were correlated. The frequency of prior infections was correlated with the impacts of all asthma triggers except allergy problems, but the frequency of recent infections was correlated only with the impacts of air pollution, cigarette smoke, respiratory infection, and nighttime hours as triggers of asthma attacks. Asthma severity was correlated with the frequencies of prior and recent respiratory infections and with the impact of respiratory infection as an asthma trigger.