Non-Gaussian diffusion MRI assessment of brain microstructure in mild cognitive impairment and Alzheimer’s disease

We report the first application of a novel diffusion-based MRI method, called diffusional kurtosis imaging (DKI), to investigate changes in brain tissue microstructure in patients with mild cognitive impairment (MCI) and AD and in cognitively intact controls. The subject groups were characterized and compared in terms of DKI-derived metrics for selected brain regions using analysis of covariance with a Tukey multiple comparison correction. Receiver operating characteristic (ROC) and binary logistic regression analyses were used to assess the utility of regional diffusion measures, alone and in combination, to discriminate each pair of subject groups. ROC analyses identified mean and radial kurtoses in the anterior corona radiata as the best individual discriminators of MCI from controls, with the measures having an area under the ROC curve (AUC) of 0.80 and 0.82, respectively. The next best discriminators of MCI from controls were diffusivity and kurtosis (both mean and radial) in the prefrontal white matter (WM), with each measure having an AUC between 0.77 and 0.79. Finally, the axial diffusivity in the hippocampus was the best overall discriminator of MCI from AD, having an AUC of 0.90. These preliminary results suggest that non-Gaussian diffusion MRI may be beneficial in the assessment of microstructural tissue damage at the early stage of MCI and may be useful in developing biomarkers for the clinical staging of AD.     

Evolution behavior of catalytically activated replication-decline in a coagulation process

We propose a catalytically activated replication-decline model of three species, in which two aggregates of the same species can coagulate themselves, an A aggregate of any size can replicate itself with the help of B aggregates, and the decline of A aggregate occurs under the catalysis of C aggregates. By means of mean-field rate equations, we derive the asymptotic solutions of the aggregate size distribution ak（t） of species A, which is found to depend strongly on the competition among three mechanisms： the self-coagulation of species A, the replication of species A catalyzed by species B, and the decline of species A catalyzed by species C. When the self-coagulation of species A dominates the system, the aggregate size distribution a~（t） satisfies the conventional scaling form. When the catalyzed replication process dominates the system, ak（t） takes the generalized scaling form. When the catalyzed decline process dominates the system, ak（t） approaches the modified scaling form.     

物理演示实验认知教学功能的初步研究

根据物理学习论中的认知理论，对物理演示实验的认知教学功能进行了初步的理论探索。     

信息呈现方式、时间压力和认知风格对网上学习的影响

检验信息呈现方式、时间压力和个体认知风格对网上学习的影响效应.包括两个实验:实验一考察信息呈现方式和个体认知风格的影响;实验二考察信息呈现方式和时间压力的影响.结果表明:(1)在学习时间受限时,超文本优于线性文本,而在学习时间宽松时,两者无显著差异;(2)当时间压力不大时,呈现内容组织图不利于学习;(3)网络使用经验可掩盖认知风格的效应.本研究结论认为:文本类型、内容组织图和时间压力对网上学习绩效存在显著的交互作用.     

Effects of Pueraria candollei var mirifica (Airy Shaw and Suvat.) Niyomdham on Ovariectomy-Induced Cognitive Impairment and Oxidative Stress in the Mouse Brain

The effects of the phytoestrogen-enriched plant Pueraria mirifica (PM) extract on ovari-ectomy (OVX)-induced cognitive impairment and hippocampal oxidative stress in mice were investigated. Daily treatment with PM and 17β-estradiol (E2) significantly elevated cognitive behavior as evaluated by using the Y maze test, the novel object recognition test (NORT), and the Morris water maze test (MWM), attenuated atrophic changes in the uterus and decreased serum 17β-estradiol levels. The treatments significantly ameliorated ovariectomy-induced oxidative stress in the hippocampus and serum by a decrease in malondialdehyde (MDA), an enhancement of superoxide dismutase, and catalase activity, including significantly down-regulated expression of IL-1β, IL-6 and TNF-α proinflammatory cytokines, while up-regulating expression of PI3K. The present results suggest that PM extract suppresses oxidative brain damage and dysfunctions in the hippocampal antioxidant system, including the neuroinflammatory system in OVX animals, thereby preventing OVX-induced cognitive impairment. The present results indicate that PM exerts beneficial effects on cognitive deficits for which menopause/ovariectomy have been implicated as risk factors.     

Brain Dynamics Altered by Photic Stimulation in Patients with Alzheimer’s Disease and Mild Cognitive Impairment

Individuals with mild cognitive impairment (MCI) are at high risk of developing Alzheimer’s disease (AD). Repetitive photic stimulation (PS) is commonly used in routine electroencephalogram (EEG) examinations for rapid assessment of perceptual functioning. This study aimed to evaluate neural oscillatory responses and nonlinear brain dynamics under the effects of PS in patients with mild AD, moderate AD, severe AD, and MCI, as well as healthy elderly controls (HC). EEG power ratios during PS were estimated as an index of oscillatory responses. Multiscale sample entropy (MSE) was estimated as an index of brain dynamics before, during, and after PS. During PS, EEG harmonic responses were lower and MSE values were higher in the AD subgroups than in HC and MCI groups. PS-induced changes in EEG complexity were less pronounced in the AD subgroups than in HC and MCI groups. Brain dynamics revealed a “transitional change” between MCI and Mild AD. Our findings suggest a deficiency in brain adaptability in AD patients, which hinders their ability to adapt to repetitive perceptual stimulation. This study highlights the importance of combining spectral and nonlinear dynamical analysis when seeking to unravel perceptual functioning and brain adaptability in the various stages of neurodegenerative diseases.     

BFF: Bayesian,Fiducial, and Frequentist Analysis of Cognitive Engagement among Cognitively Impaired Older Adults

Engagement in cognitively demanding activities is beneficial to preserving cognitive health. Our goal was to demonstrate the utility of frequentist, Bayesian, and fiducial statistical methods for evaluating the robustness of effects in identifying factors that contribute to cognitive engagement for older adults experiencing cognitive decline. We collected a total of 504 observations across two longitudinal waves of data from 28 cognitively impaired older adults. Participants’ systolic blood pressure responsivity, an index of cognitive engagement, was continuously sampled during cognitive testing. Participants reported on physical and mental health challenges and provided hair samples to assess chronic stress at each wave. Using the three statistical paradigms, we compared results from six model testing levels and longitudinal changes in health and stress predicting changes in cognitive engagement. Findings were mostly consistent across the three paradigms, providing additional confidence in determining effects. We extend selective engagement theory to cognitive impairment, noting that health challenges and stress appear to be important moderators. Further, we emphasize the utility of the Bayesian and fiducial paradigms for use with relatively small sample sizes because they are not based on asymptotic distributions. In particular, the fiducial paradigm is a useful tool because it provides more information than p values without the need to specify prior distributions, which may unduly influence the results based on a small sample. We provide the R code used to develop and implement all models.     

Performance Analysis and Optimization of a Cooperative Transmission Protocol in NOMA-Assisted Cognitive Radio Networks with Discrete Energy Harvesting

In this paper, we propose a spectrum-sharing protocol for a cooperative cognitive radio network based on non-orthogonal multiple access technology, where the base station (BS) transmits the superimposed signal to the primary user and secondary user with/without the assistance of a relay station (RS) by adopting the decode-and-forward technique. RS performs discrete-time energy harvesting for opportunistically cooperative transmission. If the RS harvests sufficient energy, the system performs cooperative transmission; otherwise, the system performs direct transmission. Moreover, the outage probabilities and outage capacities of both primary and secondary systems are analyzed, and the corresponding closed-form expressions are derived. In addition, one optimization problem is formulated, where our objective is to maximize the energy efficiency of the secondary system while ensuring that of the primary system exceeds or equals a threshold value. A joint optimization algorithm of power allocation at BS and RS is considered to solve the optimization problem and to realize a mutual improvement in the performance of energy efficiency for both the primary and secondary systems. The simulation results demonstrate the validity of the analysis results and prove that the proposed transmission scheme has a higher energy efficiency than the direct transmission scheme and the transmission scheme with simultaneous wireless information and power transfer technology.     

基于实例的化学工艺流程题错因分析*

在高考命题日益强调“素养立意”的今天,化学工艺流程题能够较好地符合高考评价体系提出的命题目标定位,体现试题的考查价值,进而服务于高考化学科目的考试功能。但从实测数据分析,考生在应对化学工艺流程题时的表现却往往并不理想。选取一道化学工艺流程题实例,通过对其进行测量学各项指标的分析,对不同能力水平考生的应答情况进行诊断分析,并针对高中生如何突破化学工艺流程题的障碍提出相关建议。     

A model of dynamics of group structures of human institutions

Given is a review of the substantial theories of cognitivist's trend and also of static and dynamic models of group structures that are based on them. A model of human institutiosn is constructed that explains the origin of balanced structures. This model is realized by a system of locally interacting automatons which are connected by a system of relations and endowed with the ability to react.