Experimental Study on Eccentric Compressive Performance of Concrete Column Strengthened with CFRP Grid Reinforced ECC Matrix

Carbon-fiber-reinforced polymer (CFRP) grid and engineered cementitious composite (ECC) were combined in this study to strengthen concrete columns. The influences of the number of layers, the overlap length of CFRP grids, and the eccentricity on the bearing capacity and rigidity of reinforced concrete columns were determined. The results show that the principal failure of the reinforced column was debonding of external ECC from FRP grids at the compressive area, edges, or sides. Significant enhancement in the ultimate bearing capacity and rigidity of eccentrically loaded columns was observed after they were externally reinforced by CFRP grids and ECC; such enhancement increased with the number of reinforced layers. Eccentricity made little difference to the enhancement rate of bearing capacity when the number of reinforced layers was the same. At different eccentricities, the composite layers at the tensile area and the compressive area had different contributions to the bearing capacity. An effective bond and efficient stress transfer could be ensured as long as the overlap length between CFRP grids reached 120 mm

Functional Connectome before and following Temporal Lobectomy in Mesial Temporal Lobe Epilepsy

As mesial temporal lobe epilepsy (mTLE) has been recognized as a network disorder, a longitudinal connectome investigation may shed new light on the understanding of the underlying pathophysiology related to distinct surgical outcomes. Resting-state functional MRI data was acquired from mTLE patients before (n = 37) and after (n = 24) anterior temporal lobectomy. According to surgical outcome, patients were classified as seizure-free (SF, n = 14) or non-seizure-free (NSF, n = 10). First, we found higher network resilience to targeted attack on topologically central nodes in the SF group compared to the NSF group, preoperatively. Next, a two-way mixed analysis of variance with between-subject factor ‘outcome’ (SF vs. NSF) and within-subject factor ‘treatment’ (pre-operation vs. post-operation) revealed divergent dynamic reorganization in nodal topological characteristics between groups, in the temporoparietal junction and its connection with the ventral prefrontal cortex. We also correlated the network damage score (caused by surgical resection) with postsurgical brain function, and found that the damage score negatively correlated with postoperative global and local parallel information processing. Taken together, dynamic connectomic architecture provides vital information for selecting surgical candidates and for understanding brain recovery mechanisms following epilepsy surgery

Hippocampus-associated causal network of structural covariance measuring structural damage progression in temporal lobe epilepsy

In mesial temporal lobe epilepsy (mTLE), the causal relationship of morphometric alterations between hippocampus and the other regions, that is, how the hippocampal atrophy leads to progressive morphometric alterations in the epileptic network regions remains largely unclear. In this study, a causal network of structural covariance (CaSCN) was proposed to map the causal effects of hippocampal atrophy on the network-based morphometric alterations in mTLE. It was hypothesized that if cross-sectional morphometric MRI data could be attributed temporal information, for example, by sequencing the data according to disease progression information, GCA would be a feasible approach for constructing a CaSCN. Based on a large cohort of mTLE patients (n = 108), the hippocampus-associated CaSCN revealed that the hippocampus and the thalamus were prominent nodes exerting causal effects (i.e., GM reduction) on other regions and that the prefrontal cortex and cerebellum were prominent nodes being subject to causal effects. Intriguingly, compensatory increased gray matter volume in the contralateral temporal region and post cingulate cortex were also detected. The method unraveled richer information for mapping network atrophy in mTLE relative to the traditional methods of stage-specific comparisons and structured covariance network. This study provided new evidence on the network spread mechanism in terms of the causal influence of hippocampal atrophy on progressive brain structural alterations in mTLE. Hum Brain Mapp 38:753-766, 2017. © 2016 Wiley Periodicals, Inc.status: publishe

Impairments of thalamic nuclei in idiopathic generalized epilepsy revealed by a study combining morphological and functional connectivity MRI.

ObjectiveNeuroimaging evidence suggested that the thalamic nuclei may play different roles in the progress of idiopathic generalized epilepsy (IGE). This study aimed to demonstrate the alterations in morphometry and functional connectivity in the thalamic nuclei in IGE.MethodsFifty-two patients with IGE characterized by generalized tonic-clonic seizures and 67 healthy controls were involved in the study. The three-dimensional high-resolution T1-weighted MRI data were acquired for voxel-based morphometry (VBM) analysis, and resting-state blood-oxygenation level functional MRI data were acquired for functional connectivity analysis. The thalamic nuclei of bilateral medial dorsal nucleus (MDN) and pulvinar, as detected with decreased gray matter volumes in patients with IGE through VBM analysis, were selected as seed regions for functional connectivity analysis.ResultsDifferent alteration patterns were found in functional connectivity of the thalamic nuclei with decreased gray matter volumes in IGE. Seeding at the MDN, decreased connectivity in the bilateral orbital frontal cortex, caudate nucleus, putamen and amygdala were found in the patients (PConclusionsSome specific impairment of thalamic nuclei in IGE was identified using morphological and functional connectivity MRI approaches. These findings may strongly support the different involvement of the thalamocortical networks in IGE

Pathological factors contributing to crossed cerebellar diaschisis in cerebral gliomas: a study combining perfusion, diffusion, and structural MR imaging

PURPOSE: To investigate imaging features of crossed cerebellar diaschisis (CCD) in cerebral gliomas, and its underlying pathophysiological mechanisms. METHODS: Thirty-three pre-surgical patients with cerebral gliomas and 33 healthy controls underwent arterial spin-labeling, diffusion tensor imaging, and high-resolution T1-weighted imaging using MRI, in order to estimate cerebral blood flow (CBF), white matter integrity, and lesion volume, respectively. Asymmetry indices of CBF in the cerebellum were used for evaluating the level of CCD in the patients. These indices were correlated with clinical variables (lesion size and position, tumor histological grade, and CBF asymmetry) and diffusion tensor imaging parameters (fractional anisotropy and number of fibers in the cortico-ponto-cerebellar pathway and across the cerebral hemispheres), respectively. RESULTS: The patients showed decreased CBF in the cerebellar hemisphere contralateral to the supratentorial tumor, and increased CBF asymmetry in the cerebellum (both P < 0.05). CCD levels in high-grade gliomas were higher than those of low-grade gliomas (P < 0.05). CCD levels were negatively correlated with the size of the supratentorial lesions, and positively correlated with FA asymmetry in the cerebral fibers (both P < 0.05). CONCLUSIONS: CCD in cerebral gliomas was specifically associated with tumor histological grade, lesion size, and white matter impairments in the hemisphere ipsilateral to the tumor. The findings implicated that observing CCD might have potential for assisting grading diagnosis of cerebral gliomas.status: publishe

Characteristics of the IGE-GTCS patients and the healthy controls.

<p>p⁺was obtained by Pearson Chi-Square,</p><p>p⁺was obtained by two-sample t test.</p

Functional connectivity of medial dorsal nucleus in IGE-GTCS patients and healthy subjects.

<p>A: functional connectivity map of MDN in healthy controls; B: functional connectivity map of MDN in patients with IGE-GTCS; C: group difference of functional connectivity map of MDN. The warm color represents that the brain regions showed positive correlation with bilateral medial dorsal nucleus (p<0.05, FWE correction). The cool color represents that the brain regions showed decreased functional connectivity in IGE-GTCS patients, the threshold was set at p<0.05 after AlphaSim correction.</p

Gray matter difference between IGE-GTCS and healthy controls, and correlation analysis between gray matter volume and epilepsy duration.

<p>The cold color denotes the brain regions having reduced gray matter volume in IGE-GTCS patients. Maps threshold were set at <i>P</i><0.01, with AlphaSim correction. According to this VBM comparison results, the bilateral medial dorsal nuclei (Red circle) and the left pulvinar (Green circle) were defined as ROIs for the subsequent functional connectivity analyses. In addition, the left medial dorsal nuclei and pulvinar showed negative correlation between gray matter volume and epilepsy duration. The red block represent the gray matter volume of IGE-GTCS patients in left medial dorsal nucleus (R = −0.39, P = 0.004), the blue rhomboid represent the gray matter volume of IGE-GTCS patients in left pulvinar (R = −0.32, P = 0.02).</p