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The microstructural characteristics of white and gray matter in mild cognitive impairment (MCI) and the early-stage of Alzheimer's disease (AD) remain unclear. This study aimed to systematically identify the microstructural damages of MCI/AD in studies using neurite orientation dispersion and density imaging (NODDI), and explore their correlations with cognitive performance. Multiple databases were searched for eligible studies. The 10 eligible NODDI studies were finally included. Patients with MCI/AD showed overall significant reductions in neurite density index (NDI) of specific white matter structures in bilateral hemispheres (left hemisphere: -0.40 [-0.53, -0.27], P < 0.001; right: -0.33 [-0.47, -0.19], P < 0.001), involving the bilateral superior longitudinal fasciculus (SLF), uncinate fasciculus (UF), the left posterior thalamic radiation (PTR), and the left cingulum. White matter regions exhibited significant increased orientation dispersion index (ODI) (left: 0.25 [0.02, 0.48], P < 0.05; right: 0.27 [0.07, 0.46], P < 0.05), including the left cingulum, the right UF, and the bilateral parahippocampal cingulum (PHC), and PTR. Additionally, the ODI of gray matter showed significant reduction in bilateral hippocampi (left: -0.97 [-1.42, -0.51], P < 0.001; right: -0.90 [-1.35, -0.45], P < 0.001). The cognitive performance in MCI/AD was significantly associated with NDI (r = 0.50, P < 0.001). Our findings highlight the microstructural changes in MCI/AD were characterized by decreased fiber orientation dispersion in the hippocampus, and decreased neurite density and increased fiber orientation dispersion in specific white matter tracts, including the cingulum, UF, and PTR. Moreover, the decreased NDI may indicate the declined cognitive level of MCI/AD patients. [ABSTRACT FROM AUTHOR]

The two-dimensional graphical nesting problem is widespread in industrial production and is an NP-complete problem. The core technology of various nesting methods is the graphical collision algorithm. In this paper, a general algorithm for geometric graphics is proposed. According to the geometrical characteristics of the packed parts, the idea of divide and conquer is adopted, and the corresponding collision strategies are designed, respectively. Two-point bidirectional collision calculation, aligned bidirectional collision and slipping calculation are proposed to determine the collision relationship between graphics. The interpolation strategy is used to reduce the computation of NFP (No-Fit-Polygon). The precise interpolation between graphics is achieved by first marking and positioning, and then sliding interpolation in both directions, which improves the interpolation efficiency. Finally, the results of the comparison test by several cases of different types show that the algorithm is effective, stable, reliable and adaptable. [ABSTRACT FROM AUTHOR]

In the grasping process of the robot, the pose of robot should adapt to the change of the object's pose. In order to avoid the cumbersome calibration and difficulty of inversion in the existing vision-based robotic arm-grasping methods, a robotic arm grasping and tracking method based on Gaussian mixture of machine vision model (MGV) are proposed. This method uses Gaussian mixture model of machine vision to build the mapping relationship between the observed variables of the object and the robot joint variables. In the learning phase, the Gaussian mixture model of machine vision is used to directly construct the mapping from the pose of the target object to the joint angle of the manipulator. In the grasping stage, the pose of the target object is acquired through the camera, and the generation probability of the pose under each Gaussian component is calculated, respectively, and the Gaussian process regression corresponding to the Gaussian component with the largest posterior probability is selected to calculate the corresponding manipulator joint angle. The experimental results show that using Gaussian mixture machine vision model can make the robot manipulator grasp and track better than using single Gaussian process model. [ABSTRACT FROM AUTHOR]

Objective: To explore the effort of cerebral small vessel disease (CSVD) on regional cerebral perfusion in patients with mild cognitive impairment (MCI) using NeuroGam™ software and evaluate the capability of brain perfusion single photon emission computed tomography (SPECT) in distinguishing MCI with and without CSVD. Methods: 34 amnestic MCI subjects entered this study, conducting neuropsychological tests, MRI and 99mTechnetium ethyl cystine dimer brain perfusion SPECT imaging. All subjects were divided into those with CSVD and those without CSVD. Perfusion value was measured with Brodmann area (BA) mapping in these two groups. Automated software (NeuroGam™) was used for semi-quantitative analyses of perfusion value and comparison with normal database. Results: Compared with normal database, perfusion levels in BAs 23-left, 28 and 36-left of MCI without CSVD group had great deviations, while perfusion levels in BAs 21, 23, 24, 25, 28, 36, 38 and 47-left of MCI with CSVD group had great deviations. Furthermore, compared with CSVD group, there was significantly lower perfusion value in BA 7-left (P < 0.001) in MCI without CSVD group. Conclusions: CSVD could interact with pathological changes related to AD, exacerbating hypoperfusion in BAs 21, 23, 28, 36, 38 while compensating for cerebral blood perfusion disorder in BA 7-left in MCI patients. Meanwhile, MCI patients with CSVD shared similar hypoperfusion with vascular cognitive impairment (VCI) in BAs 24, 25 and 47L. Brain perfusion SPECT may help improve our ability to differentiate MCI with and without CSVD. [ABSTRACT FROM AUTHOR]

Objectives: To assess the efficacy and safety of 99mTc-TRODAT-1 SPECT in diagnosing Parkinson's disease (PD).Methods: 99mTc-TRODAT-1 SPECT imaging was performed in 34 healthy controls and 96 PD patients 2.5 h later after injection. The striatal image was evaluated visually and semi-quantitively. Sensitivity and specificity of 99mTc-TRODAT-1 SPECT were analyzed according to Hoehn and Yahr scale (HYS). Based on HYS, the PD patients were divided into mild (HYS 1-2) and moderate (HYS 3-5) groups. The uptake ratios of striatum (ST) and cerebellum (CB) in contralateral, ipsilateral and bilateral striatum in different groups were calculated and analyzed. The safety was assessed.Results: The sensitivity and specificity of 99mTc-TRODAT-1 SPECT to discriminate PD patients from healthy subjects were 98.96% and 94.12% and it has perfect agreement with HYS (κ = 0.94, p < 0.001). The sensitivity to diagnose mild and moderate PD was 43.42% and 95% separately. The uptake ratio in PD patients was significantly lower than that in healthy controls (1.37 ± 0.13 vs 1.68 ± 0.18, p < 0.001). And the uptake ratio in contralateral side was markedly reduced in unilateral PD patients as compared with the ipsilateral side (1.50 ± 0.20 vs 1.46 ± 0.21, p < 0.001). The striatal uptakes in affected striatum and bilateral striatum were reduced with increasing disease severity between healthy control versus mild stage versus moderate stage in the affected striatum and bilateral striatum in PD patients. No serious adverse events or death was observed after injecting 99mTc-TRODAT-1.Conclusion: We demonstrated that 99mTc-TRODAT-1 was a safety radiotracer which can be used in clinic to diagnose PD using SPECT. [ABSTRACT FROM AUTHOR]

Dislocation, one of typical crystallographic defects in silicon, is detrimental to the minority carrier lifetime of silicon wafer. Hydrogen passivation is able to reduce the recombination activity of dislocation, however, the passivation efficacy is strongly dependent on the experimental conditions. In this paper, a model based on the theory of hydrogen charge state control is proposed to explain the passivation efficacy of dislocation correlated to the peak temperature of thermal annealing and illumination intensity. Experimental results support the prediction of the model that a mix of positively charged hydrogen and negatively charged hydrogen at certain ratio can maximise the passivation efficacy of dislocation, leading to a better power conversion efficiency of silicon solar cell with dislocation in it. [ABSTRACT FROM AUTHOR]