Near Infrared Spectroscopy (NIRS) Model-Based Prediction for Protein Content in Cowpea

Cowpea (Vigna unguiculata L. Walp) is a multi-purpose legume with high quality protein for human consumption and livestock. The objective of this work was to develop near-infrared spectroscopy (NIRS) prediction models to estimate protein content in cowpea. A total of 116 cowpea breeding lines with a wide range of protein contents (19.28 % to 32.04%) were selected to build the model using whole seed and ground seed samples. Partial least-squares discriminant analysis (PLS-DA) regression technique with different pre-treatments (derivatives, standard normal variate, and multiplicative scatter correction) were carried out to develop the protein prediction model. Results showed: 1) spectral plots of both the whole seed and ground seed showed higher spectral scatter at higher wavelengths (>1450 nm), 2) data pre-processing affects prediction accuracy for bot whole seed and ground seed samples, 3) prediction using ground seed samples (0.64 R2 0.85) is better than the whole seed (0.33 R2 0.78), and 4) the data pre-processing second derivative with standard normal variate has the best prediction (R2_whole seed = 0.78, R2_ground seed = 0.85). The results will be of interest in cowpea breeding programs aimed at improving total seed protein content.

In situ infrared, Raman and X-ray spectroscopy for the mechanistic understanding of hydrogen evolution reaction

Hydrogen production by water reduction reactions has received considerable attention because hydrogen is considered a clean-energy carrier,key for a sustainable energy future.Computational methods have been widely used to study the reaction mechanism of the hydrogen evolution reaction(HER),but the calculation results need to be supported by experimental results and direct evidence to confirm the mechanistic insights.In this review,we discuss the fundamental principles of the in situ spectroscopic strategy and a theoretical model for a mechanistic understanding of the HER.In addition,we investigate recent studies by in situ Fourier transform infrared(FTIR),Raman spectroscopy,and X-ray absorption spectroscopy(XAS) and cover new findings that occur at the catalyst-electrolyte interface during HER.These spectroscopic strategies provide practical ways to elucidate catalyst phase,reaction intermediate,catalyst-electrolyte interface,intermediate binding energy,metal valency state,and coordination environment during HER.

Application of near-infrared spectroscopy for fast germplasm analysis and classification in multi-environment using intact-seed peanut(Arachis hypogaea L.)

Peanut is a worldwide oilseed crop and the need to assess germplasm in a non-destructive manner is important for seed nutritional breeding.In this study,Near Infrared Spectroscopy(NIRS)was applied to rapidly assess germplasm variability from whole seed of 699 samples,field-collected and assembled in four genetic and environmentbased sets:one set of 300 varieties of a core-collection and three sets of 133 genotypes of an interspecific population,evaluated in three environments in a large spatial scale of two countries,Mbalmayo and Bafia in Cameroon and Nioro in Senegal,under rainfed conditions.NIR elemental spectra were gathered on six subsets of seeds of each sample,after three rotation scans,with a spectral resolution of 16 cm-1over the spectral range of867 nm to 2530 nm.Spectra were then processed by principal component analysis(PCA)coupled with Partial least squares-discriminant analysis(PLS-DA).As results,a huge variability was found between varieties and genotypes for all NIR wavelength within and between environments.The magnitude of genetic variation was particularly observed at 11 relevant wavelengths such as 1723 nm,usually related to oil content and fatty acid composition.PCA yielded the most chemical attributes in three significant PCs(i.e.,eigenvalues>10),which together captured 93%of the total variation,revealing genetic and environment structure of varieties and genotypes into four clusters,corresponding to the four samples sets.The pattern of genetic variability of the interspecific population covers,remarkably half of spectrum of the core-collection,turning out to be the largest.Interestingly,a PLS-DA model was developed and a strong accuracy of 99.6%was achieved for the four sets,aiming to classify each seed sample according to environment origin.The confusion matrix achieved for the two sets of Bafia and Nioro showed 100%of instances classified correctly with 100%at both sensitivity and specificity,confirming that their seed quality was different from each other and all other samples.Overall,NIRS chemometrics is useful to assess and distinguish seeds from different environments and highlights the value of the interspecific population and core-collection,as a source of nutritional diversity,to support the breeding efforts.

Noninvasive Detection of Cerebral Blood Flow and Blood Oxygen Based on Inductive Sensing Technology and Near Infrared Spectroscopy

The synchronous monitoring of cerebral blood flow and blood oxygen levels plays a pivotal role in the prevention,diagnosis,and treatment of cerebrovascular diseases.This study introduces a novel noninvasive device utilizing inductive sensing and near-infrared spectroscopy technology to facilitate simultaneous monitoring of cerebral blood flow and blood oxygen levels.The device consists of modules for cerebral blood flow monitoring,cerebral blood oxygen monitoring,control,communication,and a host machine.Through experiments conducted on healthy subjects,it was confirmed that the device can effectively achieve synchronous monitoring and recording of cerebral blood flow and blood oxygen signals.The results demonstrate the device’s capability to accurately measure these signals simultaneously.This technology enables dynamic monitoring of cerebral blood flow and blood oxygen signals with potential clinical applications in preventing,diagnosing,treating cerebrovascular diseases while reducing their associated harm.

锁阳中19种无机元素的NIR快速测定模型的建立与适宜测定元素筛选

目的:建立锁阳中19种无机元素含量的近红外光谱(NIR)快速测定模型,筛选适宜采用NIR技术进行测定的元素。方法:采集5个省(区)的82批锁阳样品,采用积分球漫反射方式采集样品的NIR原始光谱,采用电感耦合等离子体-质谱(ICP-MS)法测定Na、K、Ca、Mg、Fe、Zn、Mn、Co、Sr、Ni、Ag、Ba、Ti、Pb、Cr、Cd、As、Hg、Cu等19种无机元素含量的化学参考值,筛选预处理原始光谱的化学计量学方法,筛选最佳波段及因子数,以偏最小二乘法(PLS)建立NIR定量分析模型。结果:K、Ca、Mg、Mn、Co、Sr、Ti、Cr元素的决定系数R^(2)及交叉验证R^(2)均大于0.9,校正均方差(RMSEC)、预测均方差(RMSEP)及留一法交叉验证均方差(RMSECV)在0.52~2.20之间,模型预测值与真实值之间具有较好的相关性,预测性能较好;Ni、Zn元素的决定系数R^(2)及交叉验证R^(2)在0.8~0.9之间,RMSEC、RMSEP及RMSECV在0.49~1.41之间,预测值与真实值之间的相关性一般;Cu元素的决定系数R^(2)及交叉验证R^(2)在0.7~0.8之间,Na、Fe、Ag、Ba、Pb、Cd、As、Hg元素的决定系数R^(2)及交叉验证R^(2)均小于0.7,此9种元素的RMSEC、RMSEP及RMSECV在1.13~10.75之间,预测值与真实值之间的相关性较差。K、Ca、Mg、Mn、Co、Sr、Ti、Cr等8种元素的模型预测值和真实值之间的相对误差在0.04%~7.62%之间,平均预测回收率在94.12%~108.45%之间,预测值与真实值之间无显著性差异(P>0.05)。结论:锁阳中K、Ca、Mg、Mn、Co、Sr、Ti、Cr元素含量适宜采用NIR技术进行快速测定。

Near-infrared spectroscopy method for rapid proximate quantitative analysis of nutrient composition in Pacific oyster Crassostrea gigas

Glycogen,amino acids,fatty acids,and other nutrient components affect the flavor and nutritional quality of oysters.Methods based on near-infrared reflectance spectroscopy(NIRS)were developed to rapidly and proximately determine the nutrient content of the Pacific oyster Crassostreagigas.Samples of C.gigas from 19 costal sites were freeze-dried,ground,and scanned for spectral data collection using a Fourier transform NIR spectrometer(Thermo Fisher Scientific).NIRS models of glycogen and other nutrients were established using partial least squares,multiplication scattering correction first-order derivation,and Norris smoothing.The R_(C) values of the glycogen,fatty acids,amino acids,and taurine NIRS models were 0.9678,0.9312,0.9132,and 0.8928,respectively,and the residual prediction deviation(RPD)values of these components were 3.15,2.16,3.11,and 1.59,respectively,indicating a high correlation between the predicted and observed values,and that the models can be used in practice.The models were used to evaluate the nutrient compositions of 1278 oyster samples.Glycogen content was found to be positively correlated with fatty acids and negatively correlated with amino acids.The glycogen,amino acid,and taurine levels of C.gigas cultured in the subtidal and intertidal zones were also significantly different.This study suggests that C.gigas NIRS models can be a cost-effective alternative to traditional methods for the rapid and proximate analysis of various slaughter traits and may also contribute to future genetic and breeding-related studies in Pacific oysters.

Study on the secondary structure and hydration effect of human serum albumin under acidic pH and ethanol perturbation with IR/NIR spectroscopy

Human serum albumin(HSA)is the most abundant protein in plasma and plays an essential physiological role in the human body.Ethanol precipitation is the most widely used way to obtain HSA,and pH and ethanol are crucial factors affecting the process.In this study,infrared(IR)spectroscopy and near-infrared(NIR)spectroscopy in combination with chemometrics were used to investigate the changes in the secondary structure and hydration of HSA at acidic pH(5.6-3.2)and isoelectric pH when ethanol concentration was varied from 0%to 40%as a perturbation.IR spectroscopy combined with the two-dimensional correlation spectroscopy(2DCOS)analysis for acid pH system proved that the secondary structure of HSA changed significantly when pH was around 4.5.What's more,the IR spectroscopy and 2DCOS analysis showed different secondary structure forms under different ethanol concentrations at the isoelectric pH.For the hydration effect analysis,NIR spectroscopy combined with the McCabe-Fisher method and aquaphotomics showed that the free hydrogen-bonded water fluctuates dynamically,with ethanol at 0-20%enhancing the hydrogen-bonded water clusters,while weak hydrogen-bonded water clusters were formed when the ethanol concentration increased continuously from 20%to 30%.These measurements provide new insights into the structural changes and changes in the hydration behavior of HSA,revealing the dynamic process of protein purification,and providing a theoretical basis for the selection of HSA alcoholic precipitation process parameters,as well as for further studies of complex biological systems.

Infrared Spectroscopy-Based Chemometric Analysis for Lard Differentiation in Meat Samples

One of the most pressing concerns for the consumer market is the detection of adulteration in meat products due to their preciousness.The rapid and accurate identification mechanism for lard adulteration in meat products is highly necessary,for developing a mechanism trusted by consumers and that can be used to make a definitive diagnosis.Fourier Transform Infrared Spectroscopy(FTIR)is used in this work to identify lard adulteration in cow,lamb,and chicken samples.A simplified extraction method was implied to obtain the lipids from pure and adulterated meat.Adulterated samples were obtained by mixing lard with chicken,lamb,and beef with different concentrations(10%–50%v/v).Principal component analysis(PCA)and partial least square(PLS)were used to develop a calibration model at 800–3500 cm^(−1).Three-dimension PCA was successfully used by dividing the spectrum in three regions to classify lard meat adulteration in chicken,lamb,and beef samples.The corresponding FTIR peaks for the lard have been observed at 1159.6,1743.4,2853.1,and 2922.5 cm−1,which differentiate chicken,lamb,and beef samples.The wavenumbers offer the highest determination coefficient R2 value of 0.846 and lowest root mean square error of calibration(RMSEC)and root mean square error prediction(RMSEP)with an accuracy of 84.6%.Even the tiniest fat adulteration up to 10%can be reliably discovered using this methodology.

幼儿体质健康水平与工作记忆加工的差异特征:来自fNIRS的证据

目的:探讨幼儿体质健康发展水平与工作记忆加工的大脑神经关联,为幼儿体质健康促进与认知发展提供依据。方法:选取98名4~6岁学龄前儿童,按照《国民体质测定标准手册(幼儿部分)》的内容评估幼儿体质健康发展水平,采用功能性近红外光谱脑成像(fNIRS)技术,监测幼儿执行工作记忆任务时的大脑前额叶皮层血氧动力学信号,采用4(体质健康,分为优秀、良好、合格、不合格)×2(记忆难度,分为低记忆难度、高记忆难度)的混合实验设计探讨幼儿体质健康水平与大脑工作记忆时的行为学和前额叶氧合血红蛋白浓度差异。结果:1)在低记忆难度条件下,体质健康优秀组的氧合血红蛋白浓度在右侧背外侧前额叶皮层(R-DLPFC)显著大于良好组,在R-DLPFC、右侧三角部布罗卡氏区(R-PTBA)、右侧额极区(R-FPA)及左侧背外侧前额叶皮层(L-DLPFC)显著大于合格组,在L-DLPFC显著大于不合格组;2)在高记忆难度条件下,优秀组的氧合血红蛋白浓度在R-DLPFC显著大于良好组,在R-DLPFC、R-PTBA、R-FPA及L-DLPFC显著大于合格组和不合格组;良好组的氧合血红蛋白浓度在L-DLPFC和R-PTBA显著大于合格组,在R-DLPFC、R-PTBA、R-FPA及L-DLPFC显著大于不合格组,合格组的氧合血红蛋白浓度在R-DLPFC、R-FPA及L-DLPFC的氧合血红蛋白浓度显著大于不合格组;3)优秀组和良好组在高记忆难度条件下的R-DLPFC、R-PTBA、R-FPA及L-DLPFC显著大于低记忆难度条件下;4)合格组在高记忆难度条件下的R-FPA和L-DLPFC的氧合血红蛋白浓度显著大于低记忆难度条件下;5)不合格组在高记忆难度条件下的R-PTBA的氧合血红蛋白浓度显著大于低记忆难度条件下。结论:幼儿的体质健康发展水平与工作记忆存在密切关联,表现为体质健康发展水平越高,大脑在执行工作记忆任务时的前额叶相关皮层激活程度越高。

定向运动练习对大学生空间定向能力的影响:来自行为学和fNIRS的证据

探讨定向运动练习对大学生空间定向能力的影响及其脑机制,为提升人的空间认知能力提供新途径和科学依据。以48名大一学生为研究对象,随机分为实验组和对照组,对实验组进行8周定向运动练习干预,采用功能性近红外光谱成像系统(fNIRS)记录被试者大脑氧合血红蛋白(Oxy-Hb)浓度变化,分析被试者干预前后空间定向认知任务的行为表现及神经机制。结果表明:(1)定向运动练习显著提升练习者空间定向认知任务的正确率且显著优于对照组。(2)在空间定向任务中,实验组左侧腹外侧前额叶(L-VLPFC)和左侧背外侧前额叶(L-DLPFC)的Oxy-Hb激活显著降低且低于对照组。(3)实验组腹外侧前额叶(VLPFC)的Oxy-Hb浓度与正确率显著相关。研究认为,定向运动练习可以有效改善练习者的空间定向认知能力,且空间定向能力的改善效益与大脑前额叶皮层激活程度有关。定向运动练习改善练习者空间定向能力的脑机制可能是通过改变练习者的空间认知加工模式,从而促进其脑神经活动的优化。

Process Characterization of the Transesterification of Rapeseed Oil to Biodiesel Using Design of Experiments and Infrared Spectroscopy

For optimization of production processes and product quality,often knowledge of the factors influencing the process outcome is compulsory.Thus,process analytical technology(PAT)that allows deeper insight into the process and results in a mathematical description of the process behavior as a simple function based on the most important process factors can help to achieve higher production efficiency and quality.The present study aims at characterizing a well-known industrial process,the transesterification reaction of rapeseed oil with methanol to produce fatty acid methyl esters(FAME)for usage as biodiesel in a continuous micro reactor set-up.To this end,a design of experiment approach is applied,where the effects of two process factors,the molar ratio and the total flow rate of the reactants,are investigated.The optimized process target response is the FAME mass fraction in the purified nonpolar phase of the product as a measure of reaction yield.The quantification is performed using attenuated total reflection infrared spectroscopy in combination with partial least squares regression.The data retrieved during the conduction of the DoE experimental plan were used for statistical analysis.A non-linear model indicating a synergistic interaction between the studied factors describes the reactor behavior with a high coefficient of determination(R^(2))of 0.9608.Thus,we applied a PAT approach to generate further insight into this established industrial process.

EEG-fNIRS技术在神经精神疾病研究中的应用进展

通过脑电图(EEG)、功能近红外光谱成像(fNIRS)、功能磁共振成像对神经精神疾病已经开展广泛的研究与应用。近年来随着技术的不断发展,EEG与fNIRS的同步采集设备被开发且逐步应用于神经精神疾病的研究中。本文首先对EEG-fNIRS设备的同步检测与数据分析技术进行简要概述,总结脑卒中、癫痫以及其他神经精神疾病研究中EEG-fNIRS的分析方法与最新发现,并探讨研究的发展方向。

基于卷积自编码的fNIRS信号运动校正算法研究

功能性近红外光谱技术(functional near-infrared spectroscopy,fNIRS)作为一种高时间分辨率、成本低廉、便携性高的脑成像系统,近年来深受脑神经科学等研究领域的关注。但fNIRS信号中的运动伪迹会干扰后期数据分析的结果,且现有的一些算法去噪效果较为单一。因此,本文提出了一种基于多层卷积自编码的fNIRS信号运动伪迹校正算法——MCAN算法,并使用该算法对fNIRS信号中的3种运动伪迹进行校正;然后用仿真数据和实验数据对所提算法的性能进行验证,将其与现有的几种常用算法进行对比,结果表明:MCAN算法在剩余运动伪迹数量、均方误差、信噪比、皮尔逊相关系数的平方、峰峰误差几种指标上表现良好,说明所提算法可作为一种全新的fNIRS信号预处理算法。

基于fNIRS对女性不同膀胱状态下盆底肌收缩任务的前额叶激活情况

目的为探讨前额叶在人体控尿功能中发挥的作用提供神经影像学依据。方法利用近红外脑功能成像技术(fNIRS)收集20名健康成年女性志愿者膀胱充盈和空虚状态下盆底肌收缩时大脑前额皮层的血流动力学数据,并对数据进行相应的处理,通过分析各个通道所提取的氧合血红蛋白浓度的相对变化量所对应的Beta值,对比前额叶不同脑区间激活情况差异。结果膀胱充盈状态下前额皮层共有30个通道激活,膀胱空虚状态下前额皮层共有8个通道激活(P均<0.05),其中共同激活通道有7个;相较于空虚状态,膀胱充盈时的前额叶激活更明显,且以右侧脑区激活为主,差异主要体现在右侧背外侧前额叶和额极(P均<0.05)。结论盆底肌收缩运动可以使大脑前额皮层被激活。当膀胱处于充盈状态时大脑前额皮层可能会通过神经反射活动感知膀胱的压力变化,从而参与调控盆底肌的自主舒缩运动,实现其在人体控尿功能中的作用,其中右侧背外侧前额叶脑区在此过程中发挥的作用可能更为明显。

BACNN: Multi-scale feature fusion-based bilinear attention convolutional neural network for wood NIR classification

Effective development and utilization of wood resources is critical.Wood modification research has become an integral dimension of wood science research,however,the similarities between modified wood and original wood render it challenging for accurate identification and classification using conventional image classification techniques.So,the development of efficient and accurate wood classification techniques is inevitable.This paper presents a one-dimensional,convolutional neural network(i.e.,BACNN)that combines near-infrared spectroscopy and deep learning techniques to classify poplar,tung,and balsa woods,and PVA,nano-silica-sol and PVA-nano silica sol modified woods of poplar.The results show that BACNN achieves an accuracy of 99.3%on the test set,higher than the 52.9%of the BP neural network and 98.7%of Support Vector Machine compared with traditional machine learning methods and deep learning based methods;it is also higher than the 97.6%of LeNet,98.7%of AlexNet and 99.1%of VGGNet-11.Therefore,the classification method proposed offers potential applications in wood classification,especially with homogeneous modified wood,and it also provides a basis for subsequent wood properties studies.

Structure and Vibrational Spectroscopy of 2-Methylallyl Alcohol

The intramolecular O−H…πhydrogen bond has garnered significant research interest in recent decades.In this work,we utilized the infrared(IR)-vacuum-ultraviolet(VUV)nonresonant ionization detected IR spectroscopy(NRID-IR)method to study the molecular structure of neutral and cationic 2-methylallyl alcohol(MAA,CH_(2)=C(CH_(3))−CH_(2)−OH).Density functional theory calculations revealed five stable neutral and three stable cationic MAA conformers,respectively.Two neutral MAA conformers are expected to have an O−H…πintramolecular hydrogen bond interaction,based on the structural characterization that the OH group is directed toward the C=C double bond.The IR spectra of both neutral(2700−3700 cm^(−1))and cationic MAA(2500−7200 cm^(−1))were measured,and the anharmonic IR spectra were calculated at the B3LYP-D3(BJ)/def2-TZVPP level.The OH stretching vibration frequency of neutral MAA was observed at 3656 cm−1,slightly lower than those of methanol and ethanol.In contrast,the OH stretching vibration of cationic MAA was red-shifted by about 140 cm^(−1)compared to neutral MAA.The interaction region indicator and natural bond orbital analysis suggest that the O−H…πinteraction in neutral MAA is weak,and may not play a major role in stabilizing the neutral MAA.

Differential diagnosis of Crohn’s disease and intestinal tuberculosis based on ATR-FTIR spectroscopy combined with machine learning

BACKGROUND Crohn’s disease(CD)is often misdiagnosed as intestinal tuberculosis(ITB).However,the treatment and prognosis of these two diseases are dramatically different.Therefore,it is important to develop a method to identify CD and ITB with high accuracy,specificity,and speed.AIM To develop a method to identify CD and ITB with high accuracy,specificity,and speed.METHODS A total of 72 paraffin wax-embedded tissue sections were pathologically and clinically diagnosed as CD or ITB.Paraffin wax-embedded tissue sections were attached to a metal coating and measured using attenuated total reflectance fourier transform infrared spectroscopy at mid-infrared wavelengths combined with XGBoost for differential diagnosis.RESULTS The results showed that the paraffin wax-embedded specimens of CD and ITB were significantly different in their spectral signals at 1074 cm^(-1) and 1234 cm^(-1) bands,and the differential diagnosis model based on spectral characteristics combined with machine learning showed accuracy,specificity,and sensitivity of 91.84%,92.59%,and 90.90%,respectively,for the differential diagnosis of CD and ITB.CONCLUSION Information on the mid-infrared region can reveal the different histological components of CD and ITB at the molecular level,and spectral analysis combined with machine learning to establish a diagnostic model is expected to become a new method for the differential diagnosis of CD and ITB.

基于fNIRS的主动、被动与想象屈肘运动脑激活的特点及比较

目的 利用功能性近红外光谱成像(functional near-infrared spectroscopy, fNIRS)技术探究健康成年人主动屈肘、被动屈肘和想象屈肘运动脑激活的特点。方法 选取30名健康大学生为被试者,男女各15例,年龄(21.22±1.42)岁,选择右手主动、被动和想象屈肘任务作为刺激模式,采用近红外光谱脑功能成像系统实时采集被试者3种不同运动模式下脑功能区氧合血红蛋白(Oxyhemoglobin, HbO2)水平作为脑激活的特征值,并以静息态(resting state, RS)的HbO2水平为基线值,比较3种运动模式下脑激活的特点。结果 非参数检验结果表明,不同运动模式下,右侧初级运动皮层(H=13.309,P=0.004),右侧前额叶前部皮层(H=20.30,P<0.001),右侧背外侧前额叶皮层(H=12.194,P=0.007),左侧初级体感皮层(H=12.642,P=0.005),左侧初级运动皮层(H=20.03,P<0.001),左侧前额叶前部皮层(H=18.187,P<0.001),左侧背外侧前额叶皮层(H=13.379,P=0.004)的HbO2水平比较差异有统计学意义;而其右侧初级体感皮层(H=4.284,P=0.232),右侧前运动区和辅助运动皮层(H=4.201,P=0.241),左侧前运动区和辅助运动皮层(H=8.793,P=0.052)HbO2水平比较差异无统计学意义。结论 不同运动模式下存在特定的脑功能区激活,其激活程度既有相似性又有差异性,主动运动和被动运动任务下的脑激活区最类似。

Investigation of Prefrontal Cortex Activity in University Students with Presenteeism: A Near-Infrared Spectroscopy (NIRS) Study

Presenteeism refers to impaired performance attributed to attending work with health problems. There has been no study examining the state of presenteeism with objective measures. We compared cerebral hemodynamic changes, measured by near-infrared spectroscopy (NIRS), during neuropsychological tests conducted by university students with presenteeism and healthy controls. Twenty-two university students participated in the study;11 of them with impaired performance caused by mental health problem were allocated to the presenteeism group and 11 without health problems to the control group. Presenteeism was assessed by the Presenteeism Scale for Students. To evoke hemodynamics changes, the participants completed a Word Fluency Test (WFT) and a Trail Making Test (TMT). The NIRS probes were located over the bilateral prefrontal area. Students with presenteeism had significantly higher incidences of depression than controls. However, there was no significant difference in behavioral performance examinations between the two groups. With regard to hemodynamics changes, the repeated measures analysis of covariance of the NIRS signals revealed significant interactions between group and task activation. Although we observed a significant increase in oxygenated hemoglobin concentration during the WFT among controls (simple main effect;left channel, F(1, 19) = 27.34, P F(1, 19) = 22.05, P < 0.001), no changes were found in students with presenteeism during either the WFT (simple main effect;left channel, F(1, 19) = 0.12, P F(1, 19) = 0.08, P t = ﹣0.94, P with Bonferroni correction = 0.745;right channel, t = ﹣2.19, P with Bonferroni correction < 0.113). This is the first study to reveal differences in activity in the cerebral cortex associated with presenteeism. The fact that students with presenteeism have prefrontal dysfunction might reinforce the concept of presenteeism.

Simulation and Modelling of near Infrared Spectroscopy (NIRS) as Brain Monitor

Near infrared spectroscopy (NIRS) is a method for non-invasive monitoring of cerebral oxygenation and haemodynamics. Different devices provide information on changes of oxygenated (HbO2) and deoxygenated haemoglobin (HHb), oxidized cytochrome aa3 (CytOx) or regional oxygen saturation (rSO2). NIRS has been used during adult and paediatric cardiac surgery.