Three-dimensional pictures of industrial scenes applying an optical radar

For small scale ranging, a light beam, modulated with a wavelength typical for radio waves, is a suitable means of scanning. The ranging beam can be focussed to illuminate only a small spot. The diffuse reflection on the spot ensures that an echo appears. By applying phase comparison techniques to the ranging and echo beam the optical path length and thus the height of the illuminated surface element can be determined. By systematically deflecting the beam and thereby scanning the scene, a discrete height map is obtained. The realisation of such a small scale ‘optical radar’ is described, the main elements of which are a semiconductor diode laser for emission, an avalanche photo diode for detection, and a two-dimensional beam deflection mechanics for scanning. The typical performance is taking a picture of a volume of about 0·5 m × 0·5 m × 0·5 m within 1s, consisting of about 64 000 pixels.     

Evaluation and optimization of fMRI single-subject processing pipelines with NPAIRS and second-level CVA

In functional magnetic resonance imaging (fMRI) analysis, although the univariate general linear model (GLM) is currently the dominant approach to brain activation detection, there is growing interest in multivariate approaches such as principal component analysis, canonical variate analysis (CVA), independent component analysis and cluster analysis, which have the potential to reveal neural networks and functional connectivity in the brain. To understand the effect of processing options on performance of multivariate model-based fMRI processing pipelines with real fMRI data, we investigated the impact of commonly used fMRI preprocessing steps and optimized the associated multivariate CVA-based, single-subject processing pipelines with the NPAIRS (nonparametric prediction, activation, influence and reproducibility resampling) performance metrics [prediction accuracy and statistical parametric image (SPI) reproducibility] on the Fiswidgets platform. We also compared the single-subject SPIs of univariate GLM with multivariate CVA-based processing pipelines from SPM, FSL.FEAT, NPAIRS.GLM and NPAIRS.CVA software packages (or modules) using a novel second-level CVA. We found that for the block-design data, (a) slice timing correction and global intensity normalization have little consistent impact on the fMRI processing pipeline, but spatial smoothing, temporal detrending or high-pass filtering, and motion correction significantly improved pipeline performance across all subjects; (b) the combined optimization of spatial smoothing, temporal detrending and CVA model parameters on average improved between-subject reproducibility; and (c) the most important pipeline choices include univariate or multivariate statistical models and spatial smoothing. This study suggests that considering options other than simply using GLM with a fixed spatial filter may be of critical importance in determining activation patterns in BOLD fMRI studies.     

一种用于fMRI的嗅觉刺激装置设计与验证

为了实现任务态f MRI的嗅觉刺激装置的设计和功能验证.满足嗅觉f MRI实验的自动化刺激要求.首先,针对嗅觉刺激和人体嗅觉感受的特点,结合使用环境的要求,总结嗅觉f MRI的实验设计方法,归纳出用于f MRI的嗅觉刺激装置的具体需求.将刺激装置分为气路系统和控制系统、气路系统采用洁净空气通过气味溶液产生相应的气味气体,通过多支路切换达到输出不同气味的目的;控制系统采用虚拟仪器方案,其软件基于Lab VIEW平台编程,提供可输入刺激序列的人机界面,并根据要求控制电磁阀切换不同气路.然后,使用该刺激装置对单个被试进行嗅觉刺激并成像,刺激气体采用乙酸异戊酯和吡啶,实验为组块设计,使用Siemens 3.0 T MRI仪器EPI序列进行扫描,数据处理采用基于Matlab软件的SPM8和Mars Ba R工具包.选取眶额叶和岛叶中的脑激活团簇作为感兴趣区域(ROI)进行分析,激活信号在时间上的强度变化与刺激序列变化基本一致,吡啶组块的激活信号强度大于乙酸异戊酯组块激活强度,且其强度变化比乙酸异戊酯组块更符合刺激序列.ROI分析证明刺激装置基本满足嗅觉f MRI实验需要,具有较强的可用性.此外,在相同的刺激时间和间隔时间下,人脑同一区域对不同刺激气味的激活反应可能不同.     

Bootstrap generation and evaluation of an fMRI simulation database

Computer simulations have played a critical role in functional magnetic resonance imaging (fMRI) research, notably in the validation of new data analysis methods. Many approaches have been used to generate fMRI simulations, but there is currently no generic framework to assess how realistic each one of these approaches may be. In this article, a statistical technique called parametric bootstrap was used to generate a simulation database that mimicked the parameters found in a real database, which comprised 40 subjects and five tasks. The simulations were evaluated by comparing the distributions of a battery of statistical measures between the real and simulated databases. Two popular simulation models were evaluated for the first time by applying the bootstrap framework. The first model was an additive mixture of multiple components and the second one implemented a non-linear motion process. In both models, the simulated components included the following brain dynamics: a baseline, physiological noise, neural activation and random noise. These models were found to successfully reproduce the relative variance of the components and the temporal autocorrelation of the fMRI time series. By contrast, the level of spatial autocorrelation was found to be drastically low using the additive model. Interestingly, the motion process in the second model intrisically generated some slow time drifts and increased the level of spatial autocorrelations. These experiments demonstrated that the bootstrap framework is a powerful new tool that can pinpoint the respective strengths and limitations of simulation models.     

Simplified processing and characteristic investigation of DCG holographic elements

In this paper,the simplfied procedures of processing dichromated gelatin(DCG)holographic optical elements(HOE's) are presented.Both diffraction efficiency and transmis-sion of DCG grating made by the procedures have been achieved up to 97%.The diffractioncharacteristics of the DCG gratings are measured and analysed,the applications of DCG grat-ings with high quality are also discussed.     

一种用于fMRI的嗅觉刺激装置优化与验证

为搭建可用于磁共振环境下的自动控制嗅觉刺激器,本文根据刺激装置搭建的通用要求和实验室已有装置的性能提出了改进需求和系统整体设计方案．刺激装置分为控制系统与气体输送系统两部分．控制系统的软件部分基于LabVIEW平台编程,采用了虚拟仪器方案,提供可输入刺激序列的人机界面,并根据不同的刺激需求来控制电磁阀动作,以切换不同气路．气体输送系统由4条可变支路和1条恒流支路组成,其中的3条可变气路由洁净空气分别通过装有不同气味液体的洗气瓶来产生3种刺激气味．系统搭建完成后,使用霍尼韦尔AWM43600空气流量传感器测量了系统气体流量波动率为0.3%,同时测得不同刺激气路切换时的切换响应时间为1.07 s．最后使用该刺激装置对8名被试进行嗅觉刺激的同时进行功能磁共振成像（fMRI）实验,实验采用了乙醇、吡啶和乙酸异戊酯3种刺激气味,fMRI图像结果显示被试的嗅觉受到刺激后,丘脑、杏仁核、梨状皮质、眶额皮层等嗅觉相关脑区激活．以上实验表明,本文搭建的指标可量化的刺激器更能满足嗅觉fMRI实验的要求．     

A cluster-based quantitative procedure in an fMRI study of Parkinson's disease

Parkinson's disease is a neurological disorder associated with disfunction of dopaminergic pathways of the basal ganglia. In this study, we report the effects of decreasing plasma concentrations of the dopamine-agonist apomorphine on the size and extents of activity clusters observed with functional magnetic resonance imaging during a simple motor task. Eight patients at advanced disease stage and six healthy volunteers were studied during four consecutive sessions. We observed consistent activations in the primary sensorimotor area of the contralateral side and in the supplementary motor area of both patients and controls during the first session. During subsequent sessions, while the drug concentration gradually decreased in patients, they showed a fragmentation of the activity areas, with an overall decrease of involved volume and a decline of activity in the supplementary motor area. The appearing of activity in the ipsilateral motor area matched a partial recovery of supplementary motor area activation. During the last session, when patients showed severe dyskinesia, a widespread region of positive and negative correlations between signal and task was observed. We conclude that the lack of subcortical circuitry is partially reversible by apomorphine and that when the drug effects are reduced, there is a possible mechanism recruitment of alternate subcortical pathways.     

Experimental investigation of an air-magnetic-liquid resonator

Experimental results obtained by studying a vibratory system in which a magnetic liquid playing the role of a mass shuts off the cross section of a tube under the effect of a magnetic field and is spring-loaded by an air cavity and elasticity of ponderomotive type are discussed. An expression for the resonant frequency of vibrations is derived with allowance for both types of elasticity. The expression agrees well with the experimental data.     

The neural correlates of calculation ability in children: an fMRI study

Most studies investigating mental numerical processing involve adult participants and little is known about the functioning of these systems in children. The current study used functional magnetic resonance imaging (fMRI) to investigate the neural correlates of numeracy and the influence of age on these correlates with a group of adults and a group of third graders who had average to above average mathematical ability. Participants performed simple and complex versions of exact and approximate calculation tasks while in the magnet. Like adults, children activated a network of brain regions in the frontal and parietal lobes during the calculation tasks, and they recruited additional brain regions for the more complex versions of the tasks. However, direct comparisons between adults and children revealed significant differences in level of activation across all tasks. In particular, patterns of activation in the parietal lobe were significantly different as a function of age. Findings support previous claims that the parietal lobe becomes more specialized for arithmetic tasks with age.     

Power estimation predicts specific function action of acupuncture: an fMRI study

Purpose

The purpose was to investigate the distinct pattern of brain response induced by electroacupuncture stimulation (EAS) related to sustained acupuncture effects.

Material and Methods

Twenty-eight healthy volunteers were enrolled and randomized into two groups. According to grouping, volunteers were separately treated by EAS at GB37 (Guangming) or KI8 (Jiaoxin) during functional magnetic resonance imaging. Differences in acupuncture effects between the groups were tested by the power estimation approach.

Results

Spatial patterns of the whole brain power were different in the periaqueductal gray, occipital cortex (OC) and temporal cortex when induced by EAS at GB37 and KI8. Moreover, the differences in the sustained effects between these two acupoints were also identified and associated with the OC, dorsolateral prefrontal cortex, medial prefrontal cortex, anterior cingulate cortex and insula.

Conclusion

Electroacupuncture stimulation induced different power fluctuation patterns related to GB37 and KI8. We suggest that these findings might be attributed to the specific function action of these acupoints.     

Experimental investigation of the closest parallel pulses in holographic femtosecond laser processing

In holographic femtosecond laser processing, diffractive parallel pulses are distorted by phase discontinuities and mutual interference between the neighborhoods in the reconstructed image of a Fourier computer-generated hologram when the interval is smaller than the beam diameter. We investigated holographic fabrication on a glass surface using parallel pulses with different intervals. We found the closest parallel pulses with sufficient separation to avoid mutual interference in holographic femtosecond laser processing. The minimum interval was 2.8 times larger than the diffracted beam diameter. The experimental results were also supported by a computer simulation. Our findings will be very useful in the design of holographic laser processing systems.     

On an investigation of slow frequency fluctuations

The possibilities of an experimental investigation of the frequency fluctuations of the oscillations are considered by means of a digital electronic frequency meter. A comparison is made of the results of the measurements with the spectrum of the fluctuations, and an analysis of the errors of the measurements is likewise carried out.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 15, No. 4, pp. 573–579, April, 1972.     

Spinal fMRI investigation of human spinal cord function over a range of innocuous thermal sensory stimuli and study-related emotional influences

Functional magnetic resonance imaging (fMRI) of the human spinal cord has revealed important details of activity involved with innocuous sensory stimuli, including the primary input to ipsilateral dorsal gray matter and activity in bilateral ventral gray matter regions. The latter is hypothesized to reflect descending modulation from the brainstem and cortex. Here, the functions corresponding to these areas of activity are investigated by varying the temperature of innocuous thermal stimuli, and the order they are presented, across repeated fMRI experiments in the spinal cord and brainstem. Group results and connectivity analyses reveal that the ipsilateral dorsal gray matter (dGM), the primary site of sensory input, also receives inhibitory input from the rostral ventromedial medulla and the locus coeruleus, two components of the brainstem opiate analgesia system. Ipsilateral ventral gray matter (vGM) receives input from the ipsilateral dGM and inhibitory input from the pontine reticular formation, which is involved with coordination of movements by modulation of ventral horn cells. Contralateral vGM regions appear to receive input from only the ipsilateral dGM in these studies. These results provide an unprecedented view of details of human spinal cord function and descending modulation, and have important implications for assessment of the effects of spinal cord trauma and disease by means of fMRI.     

含冲击波流场干涉图的图像处理方法研究

本文研究了含冲击波流场干涉图的图像处理方法,它包括干涉条纹的快束细化算法,冲击波波阵面的提取算法和时间序列冲击波波阵面的配准算法.根据这些算法,在PC-VISION 100图像处理机上开发了应用软件.实验结果表明,该方法可用于定量计算冲击波的传播速度和压力分布,增加了流场干涉图的用途.     

Spatial investigation of an iron-doped indium phosphide ingot

A whole Czochralski-grown iron-doped indium phosphide ingot was investigated by various techniques, all along the growth axis. Scanning photoluminescence, secondary ion mass spectroscopy and sheet resistance techniques were used. The average photoluminescence intensity and the iron concentration were found to be correlated. Samples of the ingot were annealed and implanted. For low ion-implantation doses, the electrical properties were mainly dependent on the initial properties of the ingot.     

Development and investigation of an optical tilt sensor

An optical tilt sensor was developed and its performance was investigated. The tilt sensor set-up consisted of a laser light source, lenses and an image sensor. A precision reference tilt sensor was also installed on the same stage, and the measurement results of tilt angles using the optical and reference tilt sensors were correlated. The correlation coefficient (R-value) obtained under ideal conditions was 0.99454, indicating that the optical tilt sensor could produce as accurate measurements as the precision reference tilt sensor. The R-value decreased to 0.97714 and 0.93209 when the image sensor was shifted backwards and forwards from the focal plane by 1 mm, respectively. The R-value decreased to 0.96840 when the tilt sensor was performed with the room light turned on. There were not significant differences in the measurement results obtained with air conditioners turned on and off, indicating that the optical tilt sensor was robust and was not sensitive to the surrounding air turbulence. These findings are useful for the final design of the optical tilt sensor.     

Chemical and structural modifications of laser treated iron surfaces: investigation of laser processing parameters

This study focuses on the chemical, morphological and structural characterization of iron surfaces treated by laser in ambient air. Incorporation of nitrogen over a 1–2 μm thickness (10–30 at.% at the profile maximum) and superficial oxidation on 200–400 nm depth have been evidenced by nuclear reaction analyses. X-ray diffraction at grazing incidence has shown the formation of FeO and Fe₃O₄ oxide phases as well as γ-Fe(N), and ε-Fe_xN for a sufficiently high amount of nitrogen incorporated. Treatments performed with different laser beams indicate that the parameter playing the major role in surface modification processes is the wavelength. Nitrogen incorporation has been found to occur via the interaction of reactive N, present in the laser-induced plasma, and the iron molten bath. The nitriding process is promoted in the IR wavelength range. Oxidation takes place by chemical reaction during the cooling step, and is furthered in the case of UV treatment.     

Electrophysiological evidence for an early processing of human voices

Background  

Previous electrophysiological studies have identified a "voice specific response" (VSR) peaking around 320 ms after stimulus onset, a latency markedly longer than the 70 ms needed to discriminate living from non-living sound sources and the 150 ms to 200 ms needed for the processing of voice paralinguistic qualities. In the present study, we investigated whether an early electrophysiological difference between voice and non-voice stimuli could be observed.     

Modeling of NMR processing, toward efficient unattended processing of NMR experiments

Many alternative processing techniques have recently been proposed in the literature. Most of these techniques rely on specific acquisition protocols as well as on specific data processing techniques, the need for an efficient versatile and expandable NMR processing tool would be a particularly timely addition to the modern NMR spectroscopy laboratory. The work presented here consists in a modeling of the various possible NMR data processing approaches. This modeling presents a common working frame for most of the modern acquisition/processing protocols. Two different data modeling approaches are presented, strong modeling and weak modeling, depending whether the system under study or the measurement is modeled. The emphasis is placed on the weak modeling approach. This modeling is implemented in a computer program developed in python and called NPK standing (standing for NMR Processing Kernel), organized in four logical layers (i) mathematical kernel; (ii) elementary actions; (iii) processing phases; (iv) processing strategies. This organisation, along with default values for most processing parameters allows the use of the program in an unattended manner, producing close to optimal spectra. Examples are shown for 1D and 2D processing, and liquid and solid NMR spectroscopy. NPK is available from the site: http://abcis.cbs.cnrs.fr/NPK.