Brain volumetrics to investigate aging and the principal forms of degenerative cognitive decline: a brief review

The volume of the brain and of some of its structures can provide insight into the pathological process of several diseases. For this reason, in the recent years we saw a tremendous progress in the development of automated techniques for gaining information about global and regional atrophy. This paper reviews the main methods of analysis to quantify brain volume, and their application to the study of normal aging and the principal forms of degenerative dementias.     

Hippocampal volume is related to cognitive decline and fornicial diffusion measures in multiple sclerosis

Purpose

To assess for associations between hippocampal atrophy and measures of cognitive function, hippocampal magnetization transfer ratio (MTR), and diffusion measures of the fornix, the largest efferent white matter tract from the hippocampus, in patients with multiple sclerosis (MS) and controls.

Materials and Methods

A total of 53 patients with MS and 20 age- and sex-matched healthy controls participated in cognitive testing and scanning including high spatial-resolution diffusion imaging and a T1-MPRAGE scan. Hippocampal volume and fornicial thickness measures were calculated and compared to mean values of fornicial transverse diffusivity, mean diffusivity, longitudinal diffusivity, fractional anisotropy, mean hippocampal MTR, and scores on measures of episodic memory, processing speed, and working memory tasks.

Results

In patients with MS, hippocampal volume was significantly related to fornicial diffusion measures (P < 7 × 10^− 4) and to measures of verbal (P = 0.030) and visual spatial (P = 0.004) episodic memory and a measure of information processing speed (P < 0.037).

Discussion

These results highlight the role of the hippocampus in cognitive dysfunction in patients with MS and suggest that measures of hippocampal atrophy could be used to capture aspects of disease progression.     

Windows95环境中转速测量和直流电机转速控制方法

介绍在Windows95环境中用Visual Basic5.0编写转速测量和直流电机转速控制方法的过程。     

On the role of helicity in complex fluid flows

Results of direct numerical simulations of the Taylor-Green vortex are analysed by conditional sampling. In regions of small energy dissipation, there are tendencies for (1) velocity, u, and vorticity, ω, to be aligned and (2) vorticity and curl of vorticity, ? × ω, to be nearly orthogonal. The fields of dissipation, enstrophy, turbulence production, and vortex stretching exhibit a striking similarity in their spatial structure.     

高速拉丝机恒张力收线数控系统设计

介绍了一种用于高速拉丝机恒张力收线的数字控制系统。在该系统中其控制核心主要由单片机8098、转速电流输入通道、数字PID调节器等组成。系统通过对张力与电机电流和转速三个参数的实时采集和处理,能够在运行中获得良好的动静态性能。由于系统性价比高,结构简单,具有一定的实用价值和推广意义。     

Computational models of music perception and cognition I: The perceptual and cognitive processing chain

We present a review on perception and cognition models designed for or applicable to music. An emphasis is put on computational implementations. We include findings from different disciplines: neuroscience, psychology, cognitive science, artificial intelligence, and musicology. The article summarizes the methodology that these disciplines use to approach the phenomena of music understanding, the localization of musical processes in the brain, and the flow of cognitive operations involved in turning physical signals into musical symbols, going from the transducers to the memory systems of the brain. We discuss formal models developed to emulate, explain and predict phenomena involved in early auditory processing, pitch processing, grouping, source separation, and music structure computation. We cover generic computational architectures of attention, memory, and expectation that can be instantiated and tuned to deal with specific musical phenomena. Criteria for the evaluation of such models are presented and discussed. Thereby, we lay out the general framework that provides the basis for the discussion of domain-specific music models in Part II.     

Study on the noise removal processing of TV picture at high speed

This paper proposes a motion estimation method using the position estimation method of TV noise for motion picture restoration. On the basis of the block-matching used in the past, a new method is developed. The motion of the picture between the frames is calculated by the mean vector and the search position, and the search center moved is corrected by the approximated value. The method was verified as useful in this study.     

On the role of envelope fluctuation processing in spectral masking

This study examines the role of temporal cues in spectral masking, such as beats and intrinsic envelope fluctuations. Predictions from the modulation-filterbank model developed by Dau et al. [J. Acoust. Soc. Am. 102, 2906-2919 (1997)] are compared to average masking patterns from Moore et al. [J. Acoust. Soc. Am. 104, 1023-1038 (1998)]. In these experiments, tones and narrow-band noises have been used as the signal and the masker, so that all four signal-masker combinations are considered. In addition, model predictions are compared with new experimental data in conditions of notched-noise masking, where the masker consisted of two narrow-band noises whose bandwidth and frequency separation were varied systematically. The model uses a peripheral filtering stage with linear and symmetric Gammatone filters, an adaptation stage that includes a static compressive nonlinearity for stationary input stumuli and a higher sensitivity for envelope fluctuation, and a modulation filterbank that analyzes the output for each peripheral channel. For low and medium masker levels, the model accounts very well for the masking patterns in all signal-masker conditions, as well as for the notched-noise conditions. In contrast, predictions from a version of the model that acts like an energy detector account for only some of the notched-noise data, and generally do not account for the shape of the masking patterns. For a high masker level, the simulations suggest the use of asymmetric filters, with a steeper high-frequency slope than is used in the linear model, consistent with results from previous studies. In addition, several nonlinear effects become apparent at this masker level, which cannot be accounted for by the current model.     

Stable control of pulse speed in parametric three-wave solitons

We analyze the control of the propagation speed of three wave packets interacting in a medium with quadratic nonlinearity and dispersion. We find analytical expressions for mutually trapped pulses with a common velocity in the form of a three-parameter family of solutions of the three-wave resonant interaction. The stability of these novel parametric solitons is simply related to the value of their common group velocity.     

The role of collagen in bone structure: an image processing approach

Bone collagen structure in normal and pathological tissues is illustrated using techniques of thin section transmission electron microscopy and computer-assisted analysis. The normal bone collagen types, fibril architecture and diameter are described. In pathological tissue, deviations from normal fine structure are reflected in abnormal arrangements of collagen fibrils and abnormalities in fibril diameter. Computer analyses of normal fibril positive staining patterns are presented in order to provide a basis for comparing such patterns with pathological ones.     

Using heat to control the sample spinning speed in MAS NMR

A new approach using temperature to control the spinning speed of a sample rotor in magic-angle spinning NMR is presented. Instead of an electro-mechanical valve that regulates the flow of drive gas to control the spinning speed in traditional MAS NMR systems, we use a small heater wire located directly in the stator. The sample spinning speed is controlled very accurately with a surprisingly low heating power of 1 W. Results on a benchtop unit demonstrate the capability of the system.     

转子转速和流体空间对旋转法测量黏度的影响

研究了测定流体的黏度实验中转子转速和流体空间对旋转法测量黏度的影响,推导出转子偏转角与黏度测量误差之间的关系式,并应用实验数据进行了验证;流体空间对黏度测量的影响随流体空间直径的增大而减小,当流体空间直径达到102.38 mm后,测量的黏度值趋于稳定.     

The role of cognitive cueing in eliciting vocal variability

Variation in duration and frequency during three readings of each of eight sentences by 9 normal and 4 voice-disordered subjects are compared. Instructions to the subjects varied with respect to the amount and type of cognitive cueing presented in the trials, and the sentences were read in random order. Variability in fundamental frequency (F₀) was greater when pitch variation was specifically cued. Also, the portion of the sentence that was cued had greater variability in F₀ than other parts of the sentence. Variation in fundamental frequency was significantly greater in the cued versus uncued sentence trials for the voice-disordered subjects but not for the normal subjects. However, all subjects exhibited significantly greater duration for cued versus uncued readings of the same sentences. Implications for theory and practice are discussed.     

The role of peripheral resolvability in pitch-sequence processing

The authors previously reported that same/different judgments on pitch sequences were more accurate for tones with resolved (low-rank) harmonics compared to unresolved (high-rank) harmonics, even when discriminability between tones was equated [Cousineau et al. (2009). J. Acoust. Soc. Am. 126, 3179-3187]. Here, peripheral resolvability, defined by the number of harmonics per cochlear filter, was contrasted with harmonic number. Tones were presented either diotically or dichotically. In the latter case, even and odd harmonics were presented to different ears, thus halving the number of harmonics per cochlear filter. Performance was better for dichotic than for diotic presentations. This indicates that peripheral resolvability is necessary and sufficient for efficient pitch-sequence processing.     

The role of the envelope in processing iterated rippled noise.

Iterated rippled noise (IRN) is generated by a cascade of delay and add (the gain after the delay is 1.0) or delay and subtract (the gain is -1.0) operations. The delay and add/subtract operations impart a spectral ripple and a temporal regularity to the noise. The waveform fine structure is different in these two conditions, but the envelope can be extremely similar. Four experiments were used to determine conditions in which the processing of IRN stimuli might be mediated by the waveform fine structure or by the envelope. In experiments 1 and 3 listeners discriminated among three stimuli in a single-interval task: IRN stimuli generated with the delay and add operations (g = 1.0), IRN stimuli generated using the delay and subtract operations (g = -1.0), and a flat-spectrum noise stimulus. In experiment 2 the listeners were presented two IRN stimuli that differed in delay (4 vs 6 ms) and a flat-spectrum noise stimulus that was not an IRN stimulus. In experiments 1 and 2 both the envelope and waveform fine structure contained the spectral ripple and temporal regularity. In experiment 3 only the envelope had this spectral and temporal structure. In all experiments discrimination was determined as a function of high-pass filtering the stimuli, and listeners could discriminate between the two IRN stimuli up to frequency regions as high as 4000-6000 Hz. Listeners could discriminate the IRN stimuli from the flat-spectrum noise stimulus at even higher frequencies (as high as 8000 Hz), but these discriminations did not appear to depend on the pitch of the IRN stimuli. A control experiment (fourth experiment) suggests that IRN discriminations in high-frequency regions are probably not due entirely to low-frequency nonlinear distortion products. The results of the paper imply that pitch processing of IRN stimuli is based on the waveform fine structure.     

Supercritical fluid technologies for the advanced processing of plant raw materials

Publications dedicated to the application of supercritical fluids in the advanced processing of plant raw materials for the production of a wide range of products such as ethanol, liquid and gaseous fuels, sugars, organic acids, and oils are reviewed and analyzed. The specific features of the supercritical fluid technologies and their advantages over the existing traditional methods for the processing of plant raw materials are demonstrated.     

高速数据传输控制系统的设计

介绍了一种光盘数据高速传输控制系统。该系统相对计算机独立工作,可以方便灵活地组成各种数据传输控制系统,避免了计算机主机系统的介入,大大缩小了控制系统的复杂程度,避免了总线对连接设备个数的限制。使用16倍速DVD ROM,应用PIOMode4协议,在理论上该系统可以达到16 6Mbit/s的最高猝发传输速度。系统中央处理器采用单片机系统,通过内部编程,可以适应于不同的使用场合。输出端口使用数据缓冲器,以保证数据高速连续输出。     

С����EAST��ص�Դ�����źŴ����е�Ӧ���о�

用小波多分辨分析方法对EAST快控电源控制信号进行分解，分层设定阈值滤除不符合要求的频率成分再进行信号重构，得到了满足要求的EAST快控电源控制信号，并经过了仿真和实验的验证。结果表明，使用小波变换比使用其他方法更为理想。