Detection of late epilepsy by the texture analysis of MR brain images in the lithium-pilocarpine rat model

The aim of the study was to detect by texture analysis non easily visible anomalies of magnetic resonance (MR) images of piriform and entorhinal cortices relevant to the lithium-pilocarpine (Li-Pilo) model of temporal lobe epilepsy in rats. Status epilepticus was induced by Li-Pilo in twenty male rats 21 day-old. T₂-weighted MR images of their brain, were obtained before injection of Li-Pilo and one day after status epilepticus. An hyperintense signal was found in the piriform and entorhinal cortices of six rats, which developed chronic epilepsy after a latent period of one to three months. Among the 14 other rats which displayed images similar to those obtained before injection, four remained healthy but 10 rats developed late epileptic symptoms, raising the problem of hidden cortical damage which may be too subtle to be detected by classic MRI examination. A numeric treatment of digital images was then undertaken by texture analysis, to derive image information from a purely computational point of view. The combined texture and discriminant analyses based on pixels pattern anomalies, selected 3 texture parameters derived from co-occurrence matrix which characterized structural abnormalities relevant to the hyperintense signal, not only in the modified images of 6 rats but also in images of 10 rats with apparently non modified images. These three texture’s parameters allowed to classify the twenty rats of our experiment as follows: sixteen epileptic rats were effectively classified with cortical lesions, two non epileptic were correctly classified with healthy cortex, but two healthy rats were not correctly classified. This misclassification is discussed on the basis of the time dependence of the onset of seizure in the Li-Pilo model. These promising results suggest to apply this method to MRI examinations for an improvement of the early diagnostic of human epilepsy.     

Variations in adductor spasmodic dysphonia:Acoustic evidence

Acoustic analysis was used to gain information about the normal, aswell as the abnormal acoustic events associated with adductor spasmodic dysphonia (ADSD). This analysis was completed to determine whether specific acoustic events could be used to differentiate the voice of individuals with ADSD from those with normal voice. A group comparison between 14 women diagnosed with ADSD and 14 women (age-matched) with no evidence of vocal pathology or vocal dysfunction was completed. Phonatory breaks, aperiodicity, and frequency shifts, acoustic parameters previously identified in ADSD, were found throughout sustained vowel productions. The duration of the phonatory breaks and aperiodic segments was calculated and the amount of frequency shift was determined. The location of each acoustic event was marked relative to the onset of the vowel production. The subjects with ADSD presented with normal phonation and various amounts of each of the three acoustic parameters. Aperiodic segments primarily characterized the phonation of ADSD, followed by frequency shifts and phonatory breaks. The location of each of these acoustic events was within the midportion of the vowel production. The advantages of segmenting the acoustic waveform into these measures and separating the spasmodic events from normal phonation when examining laryngeal motor control of spasmodic dysphonics is discussed     

A linear piezoelectric inchworm motor using ultrasonic clamping vibrator

This paper reports a kind of linear piezoelectric inchworm motor us-ing ultrasonic clamping vibrator with ring-shaped three-pile piececonstruction.The clamping vibrator and guide shaft of the motor constitutethe friction pair.The ratio of moving friction coefficient to static one is about1:10,when the clamping vibrator is in resonance.The driving peak voltage ofthe clamping vibrator is only 120V(V_(p-p)).The velocities of the motor are0-2 mm/min,the driving force is about 0.2 kgf,and the mechanic resolvingpower is less than 50nm.The motor's technique is simple.     

Biocompatibilities of sapphire and borosilicate glass as cortical neuroprostheses

The in vivo biocompatibility of pure sapphire and borosilicate glass (BSG) implanted onto the cerebral cortex was studied via magnetic resonance imaging (MRI) and histopathology. Each implant was embedded onto the cortical surface of an adult rat brain for a total of 28 days. Rats underwent surgery with and without implants, and rats with purposely damaged cortical implant sites were also studied. Each animal was imaged via MRI before surgery as well as 10 and 28 days after the surgery. Histopathological results of animals were obtained on the 28th day to determine the specific effect on neurons. Despite the fact that sapphire has been widely used in a variety of medical implants, both MRI and histopathological results indicate that pure sapphire is not biocompatible with the cerebral cortex. On the contrary, BSG implants appear to be biocompatible with the cortical surface.     

In vivo magnetic resonance spectroscopy measurement of gray-matter and white-matter gamma-aminobutyric acid concentration in sensorimotor cortex using a motion-controlled MEGA point-resolved spectroscopy sequence

Gamma-aminobutyric acid (GABA) is a major inhibitory neurotransmitter in the brain. Understanding the GABA concentration, in vivo, is important to understand normal brain function. Using MEGA point-resolved spectroscopy sequence with interleaved water scans to detect subject motion, GABA level of sensorimotor cortex was measured using a voxel identified from a functional magnetic resonance imaging scan. The GABA level in a 20×20×20-mm³ voxel consisting of 37%±7% gray matter, 52%±12% white matter and 11%±8% cerebrospinal fluid in the sensorimotor region was measured to be 1.43±0.48 mM. In addition, using linear regression analysis, GABA concentrations within gray and white matter were calculated to be 2.87±0.61 and 0.33±0.11 mM, respectively.     

反卷积波束形成识别电机冷却系噪声辐射路径

为更准确地识别某电机冷却系噪声的辐射路径,基于FFT-NNLS反卷积波束形成方法对其进行试验研究。结果表明:相比于传统波束形成,FFT-NNLS反卷积波束形成能够显著提高分辨率,更准确地识别声源;224 Hz风扇叶片通过频率和400~1200 Hz频段的噪声水平较高,分别占声源计算面总噪声的17.7%和49.1%;冷却液入口是最主要的噪声辐射路径、进气口次之、出气口相对较弱。     

A finite volume method and experimental study of a stator of a piezoelectric traveling wave rotary ultrasonic motor

Piezoelectric traveling wave rotary ultrasonic motors are motors that generate torque by using the friction force between a piezoelectric composite ring (or disk-shaped stator) and a metallic ring (or disk-shaped rotor) when a traveling wave is excited in the stator. The motor speed is proportional to the amplitude of the traveling wave and, in order to obtain large amplitudes, the stator is excited at frequencies close to its resonance frequency. This paper presents a non-empirical partial differential equations model for the stator, which is discretized using the finite volume method. The fundamental frequency of the discretized model is computed and compared to the experimentally-measured operating frequency of the stator of Shinsei USR60 piezoelectric motor.     

Motorized Photomodulator: Making A Non-photoresponsive Supramolecular Gel Switchable by Light

Introducing photo-responsive molecules offers an attractive approach for remote and selective control and dynamic manipulation of material properties. However, it remains highly challenging how to use a minimal amount of photo-responsive units to optically modulate materials that are inherently inert to light irradiation. Here we show the application of a light-driven rotary molecular motor as a “motorized photo-modulator” to endow a typical H-bond-based gel system with the ability to respond to light irradiation and create a reversible sol-gel transition. The key molecular design feature is the introduction of a minimal amount (2 mol %) of molecular motors into the supramolecular network as photo-switchable non-covalent crosslinkers. Advantage is taken of the subtle interplay of the large geometry change during photo-isomerization of the molecular motor guest and the dynamic nature of a supramolecular gel host system. As a result, a tiny amount of molecular motors is enough to switch the mechanical modulus of the entire supramolecular systems. This study proves the concept of designing photo-responsive materials with minimum use of non-covalent light-absorbing units.     

Mapping of spikes, slow waves, and motor tasks in a patient with malformation of cortical development using simultaneous EEG and fMRI

We report on the simultaneous and continuous acquisition of EEG and functional MRI data in a patient with a left hemiparesis and focal epilepsy secondary to malformation of cortical development in the right hemisphere. EEG-triggered fMRI localization was previously demonstrated in this patient. In the experiments reported here, 322 spikes maximum at electrode C4 and 126 focal slow waves were identified offline. A hierarchy of models was explored in order to assess the relative contributions of each type of EEG event. Modeling the BOLD response to C4 spikes alone showed an area of activation within the large malformation, adjacent to the area of infolding cortex. However, also modeling slow-waves gave rise to a broader and stronger activation, suggesting that the generators overlap. Motor mapping of the right hand showed activation in the left sensorimotor cortex; left-hand tapping led to a more diffuse area of activation, displaced superiorly into the superior frontal gyrus, and a small area of activation within the lesion. In conclusion, continuous EEG-fMRI is useful to compare the functional mapping of epileptiform activity and eloquent cortices in individual patients.