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Kumar, Sawan, Varsha Sreenivasan, Partha Talukdar, Franco Pestilli i Devarajan Sridharan. "ReAl-LiFE: Accelerating the Discovery of Individualized Brain Connectomes on GPUs". Proceedings of the AAAI Conference on Artificial Intelligence 33 (17.07.2019): 630–38. http://dx.doi.org/10.1609/aaai.v33i01.3301630.
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Diffusion imaging and tractography enable mapping structural connections in the human brain, in-vivo. Linear Fascicle Evaluation (LiFE) is a state-of-the-art approach for pruning spurious connections in the estimated structural connectome, by optimizing its fit to the measured diffusion data. Yet, LiFE imposes heavy demands on computing time, precluding its use in analyses of large connectome databases. Here, we introduce a GPU-based implementation of LiFE that achieves 50-100x speedups over conventional CPU-based implementations for connectome sizes of up to several million fibers. Briefly, the algorithm accelerates generalized matrix multiplications on a compressed tensor through efficient GPU kernels, while ensuring favorable memory access patterns. Leveraging these speedups, we advance LiFE’s algorithm by imposing a regularization constraint on estimated fiber weights during connectome pruning. Our regularized, accelerated, LiFE algorithm (“ReAl-LiFE”) estimates sparser connectomes that also provide more accurate fits to the underlying diffusion signal. We demonstrate the utility of our approach by classifying pathological signatures of structural connectivity in patients with Alzheimer’s Disease (AD). We estimated million fiber whole-brain connectomes, followed by pruning with ReAl-LiFE, for 90 individuals (45 AD patients and 45 healthy controls). Linear classifiers, based on support vector machines, achieved over 80% accuracy in classifying AD patients from healthy controls based on their ReAl-LiFE pruned structural connectomes alone. Moreover, classification based on the ReAl-LiFE pruned connectome outperformed both the unpruned connectome, as well as the LiFE pruned connectome, in terms of accuracy. We propose our GPU-accelerated approach as a widely relevant tool for non-negative least squares optimization, across many domains.
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Bu, Xuan, Miao Cao, Xiaoqi Huang i Yong He. "The structural connectome in ADHD". Psychoradiology 1, nr 4 (grudzień 2021): 257–71. http://dx.doi.org/10.1093/psyrad/kkab021.
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Abstract Attention-deficit/hyperactivity disorder (ADHD) has been conceptualized as a brain dysconnectivity disorder. In the past decade, noninvasive diffusion magnetic resonance imaging (dMRI) studies have demonstrated that individuals with ADHD have alterations in the white matter structural connectome, and that these alterations are associated with core symptoms and cognitive deficits in patients. This review aims to summarize recent dMRI-based structural connectome studies in ADHD from voxel-, tractography-, and network-based perspectives. Voxel- and tractography-based studies have demonstrated disrupted microstructural properties predominantly located in the frontostriatal tracts, the corpus callosum, the corticospinal tracts, and the cingulum bundle in patients with ADHD. Network-based studies have suggested abnormal global and local efficiency as well as nodal properties in the prefrontal and parietal regions in the ADHD structural connectomes. The altered structural connectomes in those with ADHD provide significant signatures for prediction of symptoms and diagnostic classification. These studies suggest that abnormalities in the structural connectome may be one of the neural underpinnings of ADHD psychopathology and show potential for establishing imaging biomarkers in clinical evaluation. However, given that there are inconsistent findings across studies due to sample heterogeneity and analysis method variations, these ADHD-related white matter alterations are still far from informing clinical practice. Future studies with larger and more homogeneous samples are needed to validate the consistency of current results; advanced dMRI techniques can help to generate much more precise estimation of white matter pathways and assure specific fiber configurations; and finally, dimensional analysis frameworks can deepen our understanding of the neurobiology underlying ADHD.
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Sreenivasan, Varsha, Sawan Kumar, Franco Pestilli, Partha Talukdar i Devarajan Sridharan. "GPU-accelerated connectome discovery at scale". Nature Computational Science 2, nr 5 (maj 2022): 298–306. http://dx.doi.org/10.1038/s43588-022-00250-z.
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AbstractDiffusion magnetic resonance imaging and tractography enable the estimation of anatomical connectivity in the human brain, in vivo. Yet, without ground-truth validation, different tractography algorithms can yield widely varying connectivity estimates. Although streamline pruning techniques mitigate this challenge, slow compute times preclude their use in big-data applications. We present ‘Regularized, Accelerated, Linear Fascicle Evaluation’ (ReAl-LiFE), a GPU-based implementation of a state-of-the-art streamline pruning algorithm (LiFE), which achieves >100× speedups over previous CPU-based implementations. Leveraging these speedups, we overcome key limitations with LiFE’s algorithm to generate sparser and more accurate connectomes. We showcase ReAl-LiFE’s ability to estimate connections with superlative test–retest reliability, while outperforming competing approaches. Moreover, we predicted inter-individual variations in multiple cognitive scores with ReAl-LiFE connectome features. We propose ReAl-LiFE as a timely tool, surpassing the state of the art, for accurate discovery of individualized brain connectomes at scale. Finally, our GPU-accelerated implementation of a popular non-negative least-squares optimization algorithm is widely applicable to many real-world problems.
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Mansour L, Sina, Caio Seguin, Robert E. Smith i Andrew Zalesky. "Connectome spatial smoothing (CSS): Concepts, methods, and evaluation". NeuroImage 250 (kwiecień 2022): 118930. http://dx.doi.org/10.1016/j.neuroimage.2022.118930.
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Vecchio, Fabrizio, Francesca Miraglia i Paolo Maria Rossini. "Tracking Neuronal Connectivity from Electric Brain Signals to Predict Performance". Neuroscientist 25, nr 1 (20.05.2018): 86–93. http://dx.doi.org/10.1177/1073858418776891.
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The human brain is a complex container of interconnected networks. Network neuroscience is a recent venture aiming to explore the connection matrix built from the human brain or human “Connectome.” Network-based algorithms provide parameters that define global organization of the brain; when they are applied to electroencephalographic (EEG) signals network, configuration and excitability can be monitored in millisecond time frames, providing remarkable information on their instantaneous efficacy also for a given task’s performance via online evaluation of the underlying instantaneous networks before, during, and after the task. Here we provide an updated summary on the connectome analysis for the prediction of performance via the study of task-related dynamics of brain network organization from EEG signals.
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Celtikci, Pinar, David Tiago Fernandes Cabral, Yeh Fang-Cheng, Sandip S. Panesar i Juan Carlos Fernandez-Miranda. "364 Tumor Compression Effect on White Matter Pathways Revealed by Local Connectome Fingerprint". Neurosurgery 64, CN_suppl_1 (24.08.2017): 284–85. http://dx.doi.org/10.1093/neuros/nyx417.364.
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Abstract INTRODUCTION Low-grade gliomas (LGGs) are slow growing tumors that often cause infiltration and/or compression of the white matter pathways. Regular imaging modalities are no capable of revealing such a pathologic condition. Furthermore, up-to-date there is no reliable noninvasive imaging method to address this issue. Here we report that the local connectome fingerprint, an along track density measurement derived from diffusion MRI (dMRI), is capable of revealing the tumor compression effect on the surrounding white matter pathways. METHODS We acquired high angular resolution dMRI data on 16 patients diagnosed of LGG (WHO grade II). Peritumoral fiber tracts underwent qualitative and quantitative evaluation. Contralateral hemisphere counterparts were used for comparison. The local connectome fingerprint of peritumoral tract segment and their ratio to healthy side were visualized and calculated in comparison with 842 normal subjects from the Human Connectome Project. RESULTS >Our results showed significant increase in the ratios to the normal side among displaced tracts and decreases among the infiltrated tracts when compared to their healthy counterpart. Qualitative analysis of 65 peritumoral tracts revealed 9 (13.8%) unaffected, 24 (36.9%) displaced, 13 (20%) infiltrated and 19 (29.2%) tracts with a combination of displacement and infiltration. There were no disrupted tracts. The along tracks local connectome fingerprint further localizes the track segments with compression effect caused by the tumor mass. This feature cannot be observed in conventional tensor and diffusivity analysis. CONCLUSION The unique capability of local connectome fingerprint in revealing the compression and infiltration effect can provide potential diagnostic and prognostic applications in clinical intervention of patients with WHO grade-II low-grade gliomas.
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Harrison, Rebecca, Bryce Wei Quan Tan, Hong Qi Tan, Lloyd Tan, Mei Chin Lim, Clement Yong, John Kuo i Shelli Kesler. "NIMG-32. THE PREDICTIVE CAPACITY OF PRE-OPERATIVE IMAGING ANALYSIS IN DIFFUSE GLIOMA: A COMPARISON OF CONNECTOMICS, RADIOMICS, AND CLINICAL PREDICTIVE MODELS". Neuro-Oncology 22, Supplement_2 (listopad 2020): ii154—ii155. http://dx.doi.org/10.1093/neuonc/noaa215.645.
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Abstract BACKGROUND Radiomics and connectome analysis are distinct and non-invasive methods of deriving biologic information from MRI. Radiomics analyzes features intrinsic to the tumor, and connectomics incorporates data regarding the tumor and surrounding neural circuitry. In this study we used both techniques to predict glioma survival. METHODS We retrospectively identified 305 adult patients with histopathologically confirmed WHO grade II–IV gliomas who had presurgical, 3D, T1-weighted brain MRI. Available clinical variables included tumor lobe, hemisphere, multifocal nature grade, histology extent of surgical resection, patient age gender. For connectomics, we calculated nodal efficiencies, network size and degree for all pairs of 33 voxel cubes spanning the entire gray matter volume using similarity-based extraction and graph theory. Radiomic features were extracted using Pyradiomics and subjected to patient-level and population-level clustering (N=172). These clusters were then used to construct a multi-regional spatial interaction matrix for model building. Cox proportional hazards models were fit for clinical variables alone, connectomics alone, radiomics alone, connectomics+clinical and radiomics+clinical. We implemented 10-folds cross-validation and examined the mean area under the curve (AUC) across validation loops. RESULTS Median survival time was 134.2 months. The mean AUC for the clinical model was 0.79 +/- 0.01, the connectome model was 0.88 +/- 0.01, the combined connectome + clinical model was 0.93 +/- 0.01, the radiomic model was 0.64 +/- 0.05 and the radiomics+clinical model was 0.89+/-0.03. Radiomic analysis of the entire dataset as well as comparisons of radiomic+connectomics +/- clinical models are pending. CONCLUSIONS The combination of clinical variables and connectome analysis provided a more robust predictive model than other models. This suggests that connectome analysis incorporates valuable clinically-predictive information which can augment our capacity for prognostication of patients with diffuse glioma. These methods warrant further evaluation in larger prospective study of patients with diffuse glioma.
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Kopteva, J. P., A. S. Agafina, G. E. Trufanov i S. G. Scherbak. "Connectome MRI in evaluation of neurorehabilitation results in patients with multiple sclerosis (review)". Russian Journal for Personalized Medicine 3, nr 1 (23.03.2023): 43–53. http://dx.doi.org/10.18705/2782-3806-2023-3-1-43-53.
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The presented literature review is devoted to the assessment of the brain connectivity using specialized magnetic resonance imaging (MRI) techniques — resting state functional MRI and MR tractography, and the possibilities of their use in the rehabilitation of patients with multiple sclerosis (MS).MS is the leading cause of non-traumatic neurological disability in young adult patients in the Russian Federation, and its prevalence continues to grow steadily. The use of complex neurorehabilitation is the basis to improve the better functional outcome of patients suffering from this disease.At the same time, in clinical practice, the evaluation of the effectiveness of rehabilitation results is carried out purely on the basis of clinical scales. Resting state functional magnetic resonance imaging (rs-fMRI) makes it possible to identify connections between various functionally related regions of the brain without any external stimulation, as well as to assess the state of the connectome in dynamics.This review article discusses the main directions of modern methods of neurorehabilitation, assesses impairments in the DTI and rs-fMRI measurments in patients with multiple sclerosis compared with healthy volunteers, as well as changes in these parameters over time after the use of various neurorehabilitation methods aimed at restoring motor and cognitive functions.
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Gubskiy, Ilya L., Ivan S. Gumin, Maxim A. Shorikov, Mikhail M. Beregov, Leonid V. Gubsky i Vladimir G. Lelyuk. "Sex differences in the connectome of the human brain according to an MR-tractography study". Journal of Clinical Practice 13, nr 1 (15.04.2022): 5–13. http://dx.doi.org/10.17816/clinpract105017.
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Background: The gender differences in the brain anatomy play an important role in planning and analysis in a lot of studies of the brain. Despite most animal studies being performed on the animals of only one sex, clinical studies generally enroll both males and females. Keeping this fact in mind, learning the gender differences in the white matter structure is important for those studies which deal with the white matter changes. These differences should be considered on the stages of planning and evaluation of the results.
Aims: Evaluation of the gender differences in the white matter pathways in healthy subjects.
Methods: 21 women and 20 men were enrolled in the study. All the subjects underwent MR-tractography, then the anatomic connectome was composed and the differences were evaluated using the tracts quantitative anisotropy (QA) evaluation.
Results: The gender differences were found in the white matter pathways with the prevalence of quantitative anisotropy in women, observed in a larger number of tracts than in those of men. QA was prevalent in a lot of fascicli that form major pathways in both groups: corpus callosum, dominant arcuate fasciclus, inferior fronto-occipital, inferior and superior right longitudinal pathways.
Conclusions: The white matter pathways in males and females are different not only within the major tracts but also for small fascicli that form tracts.
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Chen, Hanbo, Tao Liu, Yu Zhao, Tuo Zhang, Yujie Li, Meng Li, Hongmiao Zhang i in. "Optimization of large-scale mouse brain connectome via joint evaluation of DTI and neuron tracing data". NeuroImage 115 (lipiec 2015): 202–13. http://dx.doi.org/10.1016/j.neuroimage.2015.04.050.
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Balogh, Attila, Péter Halász, Dániel Fabó i Lóránd Erőss. "Epileptic seizure propagation from the second somatic sensory area to the fronto-medial region, by insular redistribution. A case report and a connectome description". Journal of Epileptology 23, nr 1 (1.06.2015): 61–67. http://dx.doi.org/10.1515/joepi-2015-0023.
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SUMMARY Introduction. The seizure propagation phenomenon by inducing remote symptoms brings several difficulties in finding the seizure onset and delineating the epileptic network which should be taken into consideration in epilepsy surgery. By demonstrating a difficult (MRI negative) epilepsy surgery case explored with invasive presurgical evaluation we highlight the importance to recognise the secondary sensory area and to explore the the parieto-opercular-insular-medial frontal network in certain cases. A further conclusion is the consideration of the redistributory role of the insula as a special structure in the cerebral connectome, having a role in epileptic network organisation. Aims. To support the role of the insula in the organisation of an opercular – medial frontal epileptic network and to confirm Penfield’s the “second somatic sensory leg area” by way of a case report. We try to give an up to date exploration of our patient’s remote epileptic seizures by way of a connectome. Methods. The epileptic disorder was studied with intensive video EEG monitoring and two times 3T MRI. Interictal FDG (fluorodeoxyglucose) PET was also undertaken. Beside the scalp EEG and computerized frequency analysis, the evaluation was performed by invasive EEG with 2 grids and 2 strips and an insular deep electrode in addition. Electrical cortical stimulation and cortical mapping were also undertaken. Results. The video-EEG study revealed the complex seizure semiology. The left sided global somatosesensory aura in the leg, followed supplementary motor area manifestations represented a remote seizure. The seizure onset zone and the symptomatogenic zone were localised by the invasive electrophysiology. With the insular deep electrode we succeeded to explore the propagation of ictal activity to the insula and later to frontal medial surface. The PET, the negative 3T MRI results and the postprocessing morphometry confirmed the lesional origin and localised the epileptogenic area to the second somato-sensory field where a dysgenesis was located. Conclusions. By preoperative invasive video-EEG evaluation, the second somato-sensory leg area was delineated as the seizure onset zone. The resection of this area by IIb type cortical dysgenesis, resulted in a complete relief of the seizures. The invasive video-EEG revealed the peculiar role of the insula in the propagation of the epileptic seizure from the second sensory leg area to the ipsilateral fronto-medial supplemetary motor area. Our results, confirm, that the insula has a relay or node function on the parietal opercular-fronto-medial epileptic network. The connectome of the insula is a further additive of the scale-free features of the remote epileptic networks.
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Munsell, Brent C., Chong-Yaw Wee, Simon S. Keller, Bernd Weber, Christian Elger, Laura Angelica Tomaz da Silva, Travis Nesland, Martin Styner, Dinggang Shen i Leonardo Bonilha. "Evaluation of machine learning algorithms for treatment outcome prediction in patients with epilepsy based on structural connectome data". NeuroImage 118 (wrzesień 2015): 219–30. http://dx.doi.org/10.1016/j.neuroimage.2015.06.008.
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Kamagata, Koji, Andrew Zalesky, Taku Hatano, Maria Angelique Di Biase, Omar El Samad, Shinji Saiki, Keigo Shimoji i in. "Connectome analysis with diffusion MRI in idiopathic Parkinson's disease: Evaluation using multi-shell, multi-tissue, constrained spherical deconvolution". NeuroImage: Clinical 17 (2018): 518–29. http://dx.doi.org/10.1016/j.nicl.2017.11.007.
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Sip, Viktor, Meysam Hashemi, Anirudh N. Vattikonda, Marmaduke M. Woodman, Huifang Wang, Julia Scholly, Samuel Medina Villalon, Maxime Guye, Fabrice Bartolomei i Viktor K. Jirsa. "Data-driven method to infer the seizure propagation patterns in an epileptic brain from intracranial electroencephalography". PLOS Computational Biology 17, nr 2 (17.02.2021): e1008689. http://dx.doi.org/10.1371/journal.pcbi.1008689.
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Surgical interventions in epileptic patients aimed at the removal of the epileptogenic zone have success rates at only 60-70%. This failure can be partly attributed to the insufficient spatial sampling by the implanted intracranial electrodes during the clinical evaluation, leading to an incomplete picture of spatio-temporal seizure organization in the regions that are not directly observed. Utilizing the partial observations of the seizure spreading through the brain network, complemented by the assumption that the epileptic seizures spread along the structural connections, we infer if and when are the unobserved regions recruited in the seizure. To this end we introduce a data-driven model of seizure recruitment and propagation across a weighted network, which we invert using the Bayesian inference framework. Using a leave-one-out cross-validation scheme on a cohort of 45 patients we demonstrate that the method can improve the predictions of the states of the unobserved regions compared to an empirical estimate that does not use the structural information, yet it is on the same level as the estimate that takes the structure into account. Furthermore, a comparison with the performed surgical resection and the surgery outcome indicates a link between the inferred excitable regions and the actual epileptogenic zone. The results emphasize the importance of the structural connectome in the large-scale spatio-temporal organization of epileptic seizures and introduce a novel way to integrate the patient-specific connectome and intracranial seizure recordings in a whole-brain computational model of seizure spread.
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Bukkieva, T. A., M. L. Pospelova, A. Yu Efimtsev, O. V. Fionik, T. M. Alekseeva, K. A. Samochernykh, E. A. Gorbunova i in. "Functional MRI in the assessment of changes in the brain connectome in patients with post-mastectomy syndrome". Diagnostic radiology and radiotherapy 12, nr 4 (19.01.2022): 41–49. http://dx.doi.org/10.22328/2079-5343-2021-12-4-41-49.
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Introduction. In the postoperative period after total mastectomy, patients develop postmastectomy syndrome, including upper limb lymphedema and a number of neuropsychiatric disorders that affect the functional state of the brain and reduce the quality of life.Purpose of the study. Evaluation of changes in functional connectivity of the default mode network in patients with post-mastectomy syndrome using resting state functional MRI.Materials and methods. Resting state functional MRI was performed to 46 patients aged 30 to 50 years with neurological disorders in the late postoperative period (>6 months) after radical mastectomy for breast cancer, as well as 20 healthy women from the control group.Results. According to the intergroup statistical analysis, there were differences in functional connectivity of the default mode network in all 46 patients with post-mastectomy syndrome, compared to the control group (p<0,01).Conclusion. The revealed changes in the functional connectivity of the default mode network of the brain indicate the functional reorganization of the brain connectome in patients with neurological manifestations of post-mastectomy syndrome.
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Jo, Hyunjin, Dongyeop Kim, Jooyeon Song i Dae-Won Seo. "New approach of using cortico-cortical evoked potential for functional brain evaluation". Annals of Clinical Neurophysiology 23, nr 2 (29.10.2021): 69–81. http://dx.doi.org/10.14253/acn.2021.23.2.69.
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Cortico-cortical evoked potential (CCEP) mapping is a rapidly developing method for visualizing the brain network and estimating cortical excitability. The CCEP comprises the early N1 component the occurs at 10-30 ms poststimulation, indicating anatomic connectivity, and the late N2 component that appears at < 200 ms poststimulation, suggesting long-lasting effective connectivity. A later component at 200-1,000 ms poststimulation can also appear as a delayed response in some studied areas. Such delayed responses occur in areas with changed excitability, such as an epileptogenic zone. CCEP mapping has been used to examine the brain connections causally in functional systems such as the language, auditory, and visual systems as well as in anatomic regions including the frontoparietal neocortices and hippocampal limbic areas. Task-based CCEPs can be used to measure behavior. In addition to evaluations of the brain connectome, single-pulse electrical stimulation (SPES) can reflect cortical excitability, and so it could be used to predict a seizure onset zone. CCEP brain mapping and SPES investigations could be applied both extraoperatively and intraoperatively. These underused electrophysiologic tools in basic and clinical neuroscience might be powerful methods for providing insight into measures of brain connectivity and dynamics. Analyses of CCEPs might enable us to identify causal relationships between brain areas during cortical processing, and to develop a new paradigm of effective therapeutic neuromodulation in the future.
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Yang, Sihong, Dezhi Jin, Jun Liu i Ye He. "Identification of Young High-Functioning Autism Individuals Based on Functional Connectome Using Graph Isomorphism Network: A Pilot Study". Brain Sciences 12, nr 7 (5.07.2022): 883. http://dx.doi.org/10.3390/brainsci12070883.
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Accumulated studies have determined the changes in functional connectivity in autism spectrum disorder (ASD) and spurred the application of machine learning for classifying ASD. Graph Neural Network provides a new method for network analysis in brain disorders to identify the underlying network features associated with functional deficits. Here, we proposed an improved model of Graph Isomorphism Network (GIN) that implements the Weisfeiler-Lehman (WL) graph isomorphism test to learn the graph features while taking into account the importance of each node in the classification to improve the interpretability of the algorithm. We applied the proposed method on multisite datasets of resting-state functional connectome from Autism Brain Imaging Data Exchange (ABIDE) after stringent quality control. The proposed method outperformed other commonly used classification methods on five different evaluation metrics. We also identified salient ROIs in visual and frontoparietal control networks, which could provide potential neuroimaging biomarkers for ASD identification.
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ROESLER, CARLOS RODRIGO DE MELLO, RÔMULO PEDROZA PINHEIRO, ANDRÉ LUÍS ALMEIDA PIZZOLATTI, VALERIA ROMERO i HELTON LUIZ APARECIDO DEFINO. "IN VITRO MECHANICAL EVALUATION OF SPINAL FIXATION ROD CONNECTORS". Coluna/Columna 20, nr 3 (wrzesień 2021): 156–60. http://dx.doi.org/10.1590/s1808-185120212003245449.
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ABSTRACT Objective Evaluate and compare the mechanical resistance and the fatigue behavior associated with the use of three different modalities of vertebral fixation system rod connectors through in vitro pre-clinical mechanical tests developed specifically for this application (linear, lateral with square connector and lateral with oblique connector). Methods Cobalt chromium rods 5.5 mm in diameter were used and coupled with three types of connectors: a) side rod with oblique connector, b) side rod with square connector, and c) rod and linear connectors. Quasi-static mechanical four-point bending and fatigue tests were performed. The variables measured were (I) the bending moment at the yield limit, (II) the displacement at the yield limit, (III) the rigidity of the system in flexion and (IV) the number of cycles until system failure. Results The linear system presented the greatest force and the greatest moment at the yield limit, as well as the greatest stiffness equivalent to bending. All specimens with square and oblique connectors endured 2.5 million cycles in the minimum and maximum conditions of applied moment. The specimens with linear connector endured 2.5 million cycles with fractions of 40.14% of the bending moment at the yield limit, but failed with levels of 60.17% and 80.27%. Conclusions Systems with linear connectors showed greater mechanical resistance when compared to systems with square and oblique connectors. All systems supported cyclic loads that mimic in vivo demands. Level of evidence V; In vitro research.
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Burgess, Gregory C., Sridhar Kandala, Dan Nolan, Timothy O. Laumann, Jonathan D. Power, Babatunde Adeyemo, Michael P. Harms, Steven E. Petersen i Deanna M. Barch. "Evaluation of Denoising Strategies to Address Motion-Correlated Artifacts in Resting-State Functional Magnetic Resonance Imaging Data from the Human Connectome Project". Brain Connectivity 6, nr 9 (listopad 2016): 669–80. http://dx.doi.org/10.1089/brain.2016.0435.
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Zhi, Qing, i Zhengxing Guo. "Experimental evaluation of precast concrete sandwich wall panels with steel–glass fiber–reinforced polymer shear connectors". Advances in Structural Engineering 20, nr 10 (8.01.2017): 1476–92. http://dx.doi.org/10.1177/1369433216683198.
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A new shear connector is proposed in this article. The shear connector is made of steel–glass fiber–reinforced polymer material. Twelve full-scale precast insulated concrete sandwich panels were tested under flexure to analyze their flexural behavior subjected to pressure. The test program was composed of eight sandwich panels with steel–glass fiber–reinforced polymer connectors and four panels for comparison that were panels using stainless steel truss connectors, pure glass fiber–reinforced polymer pin connectors, and no connectors, respectively. Their load–deflection relationships, load–slip relationships, concrete strain profiles along the wythes cross section, as well as the strains in the steel–glass fiber–reinforced polymer W-shaped connectors were investigated in this article. The panels exhibited a composite action in terms of strength exceeding 85% with steel–glass fiber–reinforced polymer connectors and 40 mm insulation thickness. In addition, the other panels with more than 40 mm insulation layer and different diameter connectors only exhibited 26%–62% composite action. When evaluating the degree of the composite action in terms of stiffness, all sandwich panel values ranged from 6% to 26%. But the compared specimens with pure glass fiber–reinforced polymer connector and smaller diameter steel truss connector had lower level composite action less than 10%. Reasonable design of steel–glass fiber–reinforced polymer W-shaped connectors may provide high composite action for panels and prevent the strength from dropping rapidly due to the steel inner core in the connectors.
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BARBOSA, W. C. S., L. M. BEZERRA, L. CHATER i O. R. O. CAVALCANTE. "Experimental evaluation on the structural behavior of truss shear connectors in composite steel-concrete beams". Revista IBRACON de Estruturas e Materiais 12, nr 5 (październik 2019): 1157–82. http://dx.doi.org/10.1590/s1983-41952019000500010.
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Abstract The composite structures have great advantages in terms of structural and constructive aspects, with the shear connectors being decisive for obtaining the interaction between the structural elements and for the distribution of the stresses in the structure, taking advantage of the potentiality of each constituent material of the composite structure (steel and concrete). This work, through experimental studies, presents the development of a shear connector (Truss connector) proposed for use in a concrete-steel composite beam. The proposed connector is easy to implement and can serve as a viable alternative to the use of stud or U connectors. It was idealized a connector geometry that would provide low production cost, ease of execution, higher values of resistant load, efficiency as regards the relative sliding resistance between the metal profile and the concrete slab, as well as the efficiency regarding the resistance to the spacing of the slabs in relation to the metal profile (uplift). In order to evaluate the behavior of Truss connectors, 6 experimental models were constructed for push-out tests, 3 with 12.5 mm diameter Truss connectors and 3 with 19.0 mm diameter stud bolt connectors. The behavior of the models was investigated with respect to the loads of rupture, the transversal displacements between the concrete slabs and the relative vertical slide between the reinforced concrete slabs and the metallic profiles of the models. The results of the experimental analyzes provided an overview of the operation of the Truss and stud bolt connectors, with significant results that showed advantages of the Truss connector in relation to the stud connector considering the parameters analyzed in this work.
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Kim, Sungwon, Hyemin Hong i Taek Hee Han. "Experimental Evaluation of Connectors Performance for Modular Double-Skinned Composite Tubular Wind Turbine Tower". Applied Sciences 11, nr 13 (25.06.2021): 5899. http://dx.doi.org/10.3390/app11135899.
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Three types of connectors were proposed and tested for a modular double-skinned composite tubular (DSCT) wind turbine tower, which is composed of two concentric steel tubes filled with concrete between them. The three proposed types were a socket type connector, an H-type connector, and a bolted–welded with shear key connector. Using the proposed connectors, three modular DSCT tower specimens and a single-body specimen were built. Then, quasi-static tests were conducted to evaluate the performance of the three types of connectors, and their behavioral characteristics and failure modes were analyzed. The test results showed that the bolted–welded with shear key connector specimen exerted an almost equal moment resisting capacity as the single-body specimen; however, the other modular specimens exerted only half the moment resisting capacity of the single-body specimen. Moreover, the results showed that the bolted–welded with shear key connector is applicable in a modular DSCT wind turbine tower as it has equal ductility, maximum lateral displacement, and energy dissipation as the single-body specimen.
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Vogel, Stephan, Martin Kaltenhäuser, Cora Kim, Nadia Müller-Voggel, Karl Rössler, Arnd Dörfler, Stefan Schwab, Hajo Hamer, Michael Buchfelder i Stefan Rampp. "MEG Node Degree Differences in Patients with Focal Epilepsy vs. Controls—Influence of Experimental Conditions". Brain Sciences 11, nr 12 (30.11.2021): 1590. http://dx.doi.org/10.3390/brainsci11121590.
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Drug-resistant epilepsy can be most limiting for patients, and surgery represents a viable therapy option. With the growing research on the human connectome and the evidence of epilepsy being a network disorder, connectivity analysis may be able to contribute to our understanding of epilepsy and may be potentially developed into clinical applications. In this magnetoencephalographic study, we determined the whole-brain node degree of connectivity levels in patients and controls. Resting-state activity was measured at five frequency bands in 15 healthy controls and 15 patients with focal epilepsy of different etiologies. The whole-brain all-to-all imaginary part of coherence in source space was then calculated. Node degree was determined and parcellated and was used for further statistical evaluation. In comparison to controls, we found a significantly higher overall node degree in patients with lesional and non-lesional epilepsy. Furthermore, we examined the conditions of high/reduced vigilance and open/closed eyes in controls, to analyze whether patient node degree levels can be achieved. We evaluated intraclass-correlation statistics (ICC) to evaluate the reproducibility. Connectivity and specifically node degree analysis could present new tools for one of the most common neurological diseases, with potential applications in epilepsy diagnostics.
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Li, Qian, Kehong Lv, Jing Qiu i Guanjun Liu. "Research on Residual Life Prediction for Electrical Connectors Based on Intermittent Failure and Hidden Semi-Markov Model". Applied Sciences 8, nr 8 (15.08.2018): 1373. http://dx.doi.org/10.3390/app8081373.
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Based on the dynamic properties of electrical connector intermittent failure, the model and methods for residual life prediction for electrical connectors are studied in this paper. Firstly, the mechanism of electrical connector intermittent failure is analyzed, and the area enclosed by the contact resistance curve and the fault threshold is defined as the generalized severity of intermittent failure to describe how severe the electrical connector’s intermittent failure is. Then, the Hidden Semi-Markov Model (HSMM) is introduced to build the residual life prediction model of the electrical connector. Further, the evaluation method of using the state and prediction method for residual life are studied. Finally, by carrying out the residual life prediction test, the effectiveness of the residual life prediction method for electrical connectors based on intermittent failure and HSMM is verified.
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Kim, Young Ho, Jae Ho Jung, Soon Jong Yoon i Won Sup Jang. "Evaluation of Load Carrying Capacity of the Perforated Shear Connector with Flange Heads". Key Engineering Materials 326-328 (grudzień 2006): 1811–16. http://dx.doi.org/10.4028/www.scientific.net/kem.326-328.1811.
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In the construction of composite bridge structures, various types of shear connectors are usually used to provide an efficient load transfer and the composite action of two or more different materials. In the previous work conducted by authors, a new type of the shear connector was introduced, which is the perforated shear connector with flange heads (T-shaped perforated shear connector), and the structural behavior of the shear connector was discussed based on the results of push-out tests. For the practical design of new shear connector, it is necessary to develop the equation for the prediction of the load carrying capacity of the shear connector. In this study, the existing design equations for the Perfobond shear connector were briefly analyzed and the equation for the prediction of the shear capacity of T-shaped perforated shear connector was suggested empirically. By comparing the results obtained by the suggested equation, the existing equations for the Perfobond shear connector, and the experiment, the applicability and effectiveness of the suggested equation was estimated.
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Zenati, Marco A., Ali Sonel, Brack Hattler, A. Laurie Shroyer, Joseph Collins, John Messenger, Janet H. Baltz i in. "Patency Outcomes of Aortic Connectors". Innovations: Technology and Techniques in Cardiothoracic and Vascular Surgery 1, nr 5 (wrzesień 2006): 255–57. http://dx.doi.org/10.1097/01.imi.0000229898.22601.55.
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Objective Controlled outcome analysis of mechanical aortic connectors for proximal saphenous vein bypass graft anastomosis is lacking. We report the clinical and angiographic outcome of patients receiving the Symmetry aortic connector (St. Jude Medical, Inc St. Paul, MN, US) within a multicenter, prospective, randomized study. Methods Twenty-five patients at 3 study sites received aortic connectors at the time of coronary artery bypass surgery. Protocol-defined angiographic follow-up was completed in 19 of 25 patients (76%) at time-points up to 14 months postoperatively; 32 connector anastomoses were evaluated in these 19 patients. Beating heart surgery was performed in 17 patients, and 2 were performed with cardiopulmonary bypass. Age was 69.7 ± 8.1 year; all patients were males. Results The connector anastomosis patency rate was 15.6% (5/32). There were no deaths during the follow-up period. Four patients (21%) suffered myocardial infarction and 2 additional patients (10.5%) required percutaneous coronary interventions; one of who required 3 percutaneous coronary interventions, the other received one percutaneous coronary intervention. Conclusions In this nonrandomized cohort of patients, occlusion rate with Symmetry connectors was significantly greater than anticipated. Patients who have received these connectors during coronary artery bypass surgery may require closer follow-up and evaluation. While the manufacturer has stopped producing this device, there has been no recall of the product, clinical support remains ongoing, and next generation connectors have now been marketed. Consideration should be given to discontinuation of the clinical use of Symmetry connectors.
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Song, Xuemin, Weiqin Liu i Hao Wu. "Investigation on Load Characteristics of Hinged Connector for a Large Floating Structure Model under Wave Actions". Journal of Marine Science and Engineering 11, nr 4 (5.04.2023): 786. http://dx.doi.org/10.3390/jmse11040786.
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The super-large floating bodies are often designed as multimodule structures linked by connectors, and the load and strength evaluation of the connector structure becomes an essential work in the design procedure of these floating bodies. In this paper, the hydrodynamic experimental model of a double floating body with a hinged connecter is designed first, and a hinged connector is adopted for connecting the double module floating bodies. A test is conducted for load calibration. Then, the experiments are carried out in the towing tank under different wave conditions. The load characteristics of the hinged connector are measured in the experiment. The numerical simulations for the load of the hinged connector are conducted based on the commercial platform ANSYS. The time history of the vertical, lateral and longitudinal loads for the hinged connector are illustrated. Finally, the comparison and analysis between the experimental results and numerical results is presented, and the conclusions are drawn, which indicate that the numerical method is effective to predict the load characteristics of a hinged connector. Above all, the methods and conclusions of this study are used to provide reference and guidance for the structural design of hinged connectors for floating bodies.
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Patela, Dr Ashish, Dr Dipika Sathvara, Dr Himanshu Patel i Dr C. Chakrabarti Dr.C.Chakrabarti. "Evaluation of Antinuclear Antibody in Connective Tissue Disorders". International Journal of Scientific Research 3, nr 6 (1.06.2012): 19–21. http://dx.doi.org/10.15373/22778179/june2014/8.
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Wang, Ruoyu, Liangjun Xu i Yilin Zhou. "A Systematic Approach for the Reliability Evaluation of Electric Connector". Journal of Electrical and Computer Engineering 2021 (5.05.2021): 1–18. http://dx.doi.org/10.1155/2021/5514674.
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Under the trend of high density and miniaturization, the current that the connector transmits per unit volume is getting higher and higher, which makes the reliability design of the connector more challenging. Under the pressure of high performance and low cost requirements, the design has to be more accurate and more efficient. Thus, in the design process, a systematic approach for reliability evaluation is required. However, there is no valid enough approach that is integrated, well-organized, and quantitative. In this article, a systematic approach for the reliability evaluation of connector was proposed, and by applying it on a typical object named a blade-spring connector, the validity of this approach was verified. After the framework of this approach has been established, the methods and models needed were provided, including the method to build up material selection criterion and the assessment models of stress relaxation, thermal diffusion, and sliding wear, respectively. Then, the feasibility of a newly developed copper alloy on the connector and the reliability behaviors of this connector were determined through this approach. The unsatisfactory aspects of reliability were pointed out and some possible redesign choices were provided. Results and discussion revealed that the proposed approach is a helpful tool for designing electric connectors, especially on the reliability design.
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Burks, Joshua D., Andrew K. Conner, Phillip A. Bonney, Chad A. Glenn, Cordell M. Baker, Lillian B. Boettcher, Robert G. Briggs, Daniel L. O’Donoghue, Dee H. Wu i Michael E. Sughrue. "Anatomy and white matter connections of the orbitofrontal gyrus". Journal of Neurosurgery 128, nr 6 (czerwiec 2018): 1865–72. http://dx.doi.org/10.3171/2017.3.jns162070.
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OBJECTIVEThe orbitofrontal cortex (OFC) is understood to have a role in outcome evaluation and risk assessment and is commonly involved with infiltrative tumors. A detailed understanding of the exact location and nature of associated white matter tracts could significantly improve postoperative morbidity related to declining capacity. Through diffusion tensor imaging–based fiber tracking validated by gross anatomical dissection as ground truth, the authors have characterized these connections based on relationships to other well-known structures.METHODSDiffusion imaging from the Human Connectome Project for 10 healthy adult controls was used for tractography analysis. The OFC was evaluated as a whole based on connectivity with other regions. All OFC tracts were mapped in both hemispheres, and a lateralization index was calculated with resultant tract volumes. Ten postmortem dissections were then performed using a modified Klingler technique to demonstrate the location of major tracts.RESULTSThe authors identified 3 major connections of the OFC: a bundle to the thalamus and anterior cingulate gyrus, passing inferior to the caudate and medial to the vertical fibers of the thalamic projections; a bundle to the brainstem, traveling lateral to the caudate and medial to the internal capsule; and radiations to the parietal and occipital lobes traveling with the inferior fronto-occipital fasciculus.CONCLUSIONSThe OFC is an important center for processing visual, spatial, and emotional information. Subtle differences in executive functioning following surgery for frontal lobe tumors may be better understood in the context of the fiber-bundle anatomy highlighted by this study.
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Xu, Xiaohan, i Yuguang Huang. "Objective Pain Assessment: a Key for the Management of Chronic Pain". F1000Research 9 (23.01.2020): 35. http://dx.doi.org/10.12688/f1000research.20441.1.
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The individual and social burdens associated with chronic pain have been escalating globally. Accurate pain measurement facilitates early diagnosis, disease progression monitoring and therapeutic efficacy evaluation, thus is a key for the management of chronic pain. Although the “golden standards” of pain measurement are self-reported scales in clinical practice, the reliability of these subjective methods could be easily affected by patients’ physiological and psychological status, as well as the assessors’ predispositions. Therefore, objective pain assessment has attracted substantial attention recently. Previous studies of functional magnetic resonance imaging (fMRI) revealed that certain cortices and subcortical areas are commonly activated in subjects suffering from pain. Dynamic pain connectome analysis also found various alterations of neural network connectivity that are correlated with the severity of clinical pain symptoms. Electroencephalograph (EEG) demonstrated suppressed spontaneous oscillations during pain experience. Spectral power and coherence analysis of EEG also identified signatures of different types of chronic pain. Furthermore, fMRI and EEG can visualize objective brain activities modulated by analgesics in a mechanism-based way, thus bridge the gaps between animal studies and clinical trials. Using fMRI and EEG, researchers are able to predict therapeutic efficacy and identify personalized optimal first-line regimens. In the future, the emergence of magnetic resonance spectroscopy and cell labelling in MRI would encourage the investigation on metabolic and cellular pain biomarkers. The incorporation of machine learning algorithms with neuroimaging or behavior analysis could further enhance the specificity and accuracy of objective pain assessments.
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Przywara-Chowaniec, Brygida, Sebastian Seget, Maria Dróżdż, Agata Puzio, Zenon Czuba, Ewa Nowalany-Kozielska, Damian Kawecki i Maciej Gawlikowski. "Ocena stanu antyoksydacyjnego w wybranych chorobach układowych tkanki łącznej". Annales Academiae Medicae Silesiensis 72 (20.06.2018): 116–20. http://dx.doi.org/10.18794/aams/76443.
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Sato, T., S. Sano, K. Ishikawa i T. Nakano. "Finite Element Analysis and Fatigue Evaluation of the Threaded Marine Riser Connector". Journal of Energy Resources Technology 110, nr 2 (1.06.1988): 85–92. http://dx.doi.org/10.1115/1.3231370.
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Finite element analyses were conducted of the threaded marine riser connector which has the main, internal, and external shoulder seals. The objectives of the analyses are to evaluate the fatigue resistance, strength, and seal capability of the connector under the bending, tensile, internal and external pressure loads. An element which models the bending effect in an axisymmetric body is developed and implemented into the computer program ADINA. Using the program, stress concentration factors at the corner and threaded parts of the connector under these loads are obtained. The large contribution of both shoulders to the reduction of the stress concentration factors is found to be quite clear. The seal mechanism and the stress response of the connectors are also clarified. The fatigue evaluation based on ASME Boiler and Pressure Vessel Code, Sec. III, Rules for Construction of Nuclear Power Plant Components, Division 1, Subsection NB are compared with the experimental results.
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Lee, Jun-Seop, Jong-Hun Woo, Kyung-Jae Shin i Hee-Du Lee. "Design Methodology of U-Shaped Infilled Composite Beams with Angled Shear Connectors Using Finite Element Analysis". Buildings 13, nr 9 (31.08.2023): 2221. http://dx.doi.org/10.3390/buildings13092221.
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A composite beam is a structural member that behaves as a single unit by using shear connectors between a concrete slab and an I-shaped steel girder. The composite ratio is crucial and is determined by the shear connectors’ ability to withstand the horizontal shear forces between the concrete and steel girder. In this study, a U-shaped composite beam was designed, which differs from conventional composite beams as it allows the use of a steel girder as a formwork. Moreover, angle-type shear connectors, instead of stud-type connectors, were employed. Based on this design, large-scale U-shaped composite beams with angle-type shear connectors were fabricated, and load tests were conducted to analyze the behavior after composite action and the influence of shear connector spacing. Additionally, the strength of the angle-type shear connectors used in this paper was evaluated through finite element analysis. Finally, a strength evaluation method for composite beams of this configuration is proposed.
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Seoane, Fernando, Azadeh Soroudi, Ke Lu, David Nilsson, Marie Nilsson, Farhad Abtahi i Mikael Skrifvars. "Textile-Friendly Interconnection between Wearable Measurement Instrumentation and Sensorized Garments—Initial Performance Evaluation for Electrocardiogram Recordings". Sensors 19, nr 20 (12.10.2019): 4426. http://dx.doi.org/10.3390/s19204426.
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The interconnection between hard electronics and soft textiles remains a noteworthy challenge in regard to the mass production of textile–electronic integrated products such as sensorized garments. The current solutions for this challenge usually have problems with size, flexibility, cost, or complexity of assembly. In this paper, we present a solution with a stretchable and conductive carbon nanotube (CNT)-based paste for screen printing on a textile substrate to produce interconnectors between electronic instrumentation and a sensorized garment. The prototype connectors were evaluated via electrocardiogram (ECG) recordings using a sensorized textile with integrated textile electrodes. The ECG recordings obtained using the connectors were evaluated for signal quality and heart rate detection performance in comparison to ECG recordings obtained with standard pre-gelled Ag/AgCl electrodes and direct cable connection to the ECG amplifier. The results suggest that the ECG recordings obtained with the CNT paste connector are of equivalent quality to those recorded using a silver paste connector or a direct cable and are suitable for the purpose of heart rate detection.
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Nicolau, Antoniu, Mihai Alin Pop i Camelia Coșereanu. "3D Printing Application in Wood Furniture Components Assembling". Materials 15, nr 8 (15.04.2022): 2907. http://dx.doi.org/10.3390/ma15082907.
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Additive manufacturing (AM) is used in many fields and is a method used to replace wood components or wood-jointed furniture components in the furniture industry. Replacing wood joints by 3D printed connectors would be an advantage, considering the fact that during the process of assembling furniture, the execution technology of the joints is difficult, time-consuming, and labor-intensive. Advanced technology of AM applied in furniture manufacturing helps the designers to create new concepts of product design, with no limits of shape, number of joints, color, or size. The diversity of 3D printers and AM technologies provides the selection of materials in relation with the applicability of the 3D printed object. In this respect, the objective of the present research is to design a 3D printed connector to be used for jointing three chair components, namely the leg and two stretchers made from larch (Larix decidua Mill.) wood, and to use reinforced polylactic acid (PLA) fiberglass (20 wt. %) filament for 3D printing this connector using AM with fused filament fabrication (FFF) technology. The design of the connector, the possibility of using this type of material, and the deposition method of filament were investigated in this research. For this purpose, several evaluation methods were applied: microscopic investigation with 50×, 100×, and 200× magnifications, both of the filament and of the 3D printed connector; mechanical testing of corner joint formed with the help of connector between chair leg and the two stretchers; and a microscopic investigation of the connectors’ defects that occurred after applying the compression and tensile loads on the diagonal direction of the L-type joint. The microscopic investigation of the composite filament revealed the agglomerations of glass fibers into the core matrix and areas where the distribution of the reinforcements was poor. The heterogeneous structure of the filament and the defects highlighted in the 3D printed connectors by the microscopic investigation contributed to the mechanical behavior of L-type connecting joints. The bending moments resulting from compression and tensile tests of the 3D printed connectors were compared to the results recorded after testing, under the same conditions, the normal mortise–tenon joint used to assemble the abovementioned chair components. The larch wood strength influenced the mechanical results and the conclusions of the microscopic investigations, as well as the analysis of the broken connectors after testing recommended the change of connector design and filament deposition direction.
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Diegeler, Anno, Marek Setina, Carlo Antona, Fitsum Lakew, Alex Mokracek, Roberto Scrofani, Friedrich S. Eckstein, Michael Gibson, Luis Bonilla i Thierry Carrel. "Prospective Evaluation of the St. Jude Medical Aortic Connector for Aortic-to-Autologous Vessel Graft Anastomoses". Innovations: Technology and Techniques in Cardiothoracic and Vascular Surgery 1, nr 2 (grudzień 2005): 79–82. http://dx.doi.org/10.1097/01.imi.0000190492.41439.8c.
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Background Evolving technologies of proximal anastomosis devices meet the endeavor of surgeons to minimize manipulation of the ascending aorta during surgical myocardial revascularization. The objective of this study was to compare the patency rate of the saphenous vein coronary bypass grafts in which the proximal anastomoses were performed with automatic connector devices to the suture technique. Methods From September 2002 through July 2003, 86 patients underwent coronary artery bypass grafting with at least 1 vein graft anastomosed to the ascending aorta with the Symmetry G2 connector. Six-month clinical and angiographic follow-up, including Core-Lab quantitative coronary angiography (QCA) and corrected TIMI frame count (CTFC), was performed. Results Eighty patients had at least 1 connector successfully implanted. Freedom from MACE (cardiac mortality myocardial infarction and target vessel reintervention) was 72/80 (90%). Six patients underwent a target vessel reintervention on the connector grafts. Six-month (mean 193 ± 36 days) angiography patency rates for the connector grafts were 72/81 (88.89%), 37/40 (92.5%) in sutured grafts, and 60/62 (96.8%) in arterial grafts. By QCA, 64/65 (98.5%) patent connector-grafts were free from more than 50% stenosis (1 connector-graft with a 51% stenosis). CTFC showed 65/65 (100%) patent connector-grafts with nonrestrictive flow. Conclusions Saphenous vein grafts anastomosed to the aorta with the Symmetry G2 connector have early and midterm patency rates comparable to the conventional sutured anastomoses. These results support the efficiency of the second generation of symmetry aortic connectors.
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Kim, Y. H., S. K. You, Jae Ho Jung, Soon Jong Yoon i Seung Sik Lee. "An Experimental Study on the Shear Behavior of Perforated Shear Connector with Flange Head". Key Engineering Materials 306-308 (marzec 2006): 1349–54. http://dx.doi.org/10.4028/www.scientific.net/kem.306-308.1349.
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Concrete-steel composite members are formed by bonding a steel component, such as an I-section beam, to a concrete component, such as a reinforced concrete slab, so that the two components can act as a unit. The use of such type of composite member becomes main stream of construction technology since it provides efficient load resisting mechanism in structural system. In a composite member, bond between steel and concrete is a crucial factor for the composite action. Usually this bond behavior is achieved by installation of mechanical device so called shear connector. The composite action can be divided into two categories (i.e., full and partial) depending on the shear strength of mechanical shear connector embedded in the concrete, i.e., understanding of shear load resisting mechanism is necessary to develop a new shear connector for better, wider and more efficient application of composite action. For this purpose, the push-out tests are performed for the evaluation of several existing shear connectors including carefully designed perforated shear connector with flange head. One of the purposes of this experimental research is to define the shear resisting mechanism of the proposed new type shear connector. The experimental results show that the degree of composite action using perforated shear connector with flange head is superior to those of existing shear connectors such as a general headed stud, perfobond, etc. The experimental parameters, such as the number of perforated holes, the distance between perforated holes, and the height of shear connector, are carefully chosen for the verification of their effect on the capacity of shear resistance. From this experimental investigation it was found that the mechanical performance of proposed shear connector was efficient as a rigid shear connector.
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Nam, Haewon, Chongwon Pae, Jinseok Eo, Maeng-Keun Oh i Hae-Jeong Park. "Inter-species cortical registration between macaques and humans using a functional network property under a spherical demons framework". PLOS ONE 16, nr 10 (21.10.2021): e0258992. http://dx.doi.org/10.1371/journal.pone.0258992.
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Systematic evaluation of cortical differences between humans and macaques calls for inter-species registration of the cortex that matches homologous regions across species. For establishing homology across brains, structural landmarks and biological features have been used without paying sufficient attention to functional homology. The present study aimed to determine functional homology between the human and macaque cortices, defined in terms of functional network properties, by proposing an iterative functional network-based registration scheme using surface-based spherical demons. The functional connectivity matrix of resting-state functional magnetic resonance imaging (rs-fMRI) among cortical parcellations was iteratively calculated for humans and macaques. From the functional connectivity matrix, the functional network properties such as principal network components were derived to estimate a deformation field between the human and macaque cortices. The iterative registration procedure updates the parcellation map of macaques, corresponding to the human connectome project’s multimodal parcellation atlas, which was used to derive the macaque’s functional connectivity matrix. To test the plausibility of the functional network-based registration, we compared cortical registration using structural versus functional features in terms of cortical regional areal change. We also evaluated the interhemispheric asymmetry of regional area and its inter-subject variability in humans and macaques as an indirect validation of the proposed method. Higher inter-subject variability and interhemispheric asymmetry were found in functional homology than in structural homology, and the assessed asymmetry and variations were higher in humans than in macaques. The results emphasize the significance of functional network-based cortical registration across individuals within a species and across species.
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Osmanlioglu, Yusuf, Drew Parker, Steven Brem, Ali Shokoufandeh i Ragini Verma. "NIMG-69. PERSONALIZED CONNECTOMIC SIGNATURES: BRIDGING THE GAP BETWEEN NEURO-ONCOLOGY AND CONNECTOMICS". Neuro-Oncology 22, Supplement_2 (listopad 2020): ii163. http://dx.doi.org/10.1093/neuonc/noaa215.682.
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Abstract PURPOSE Connectomics has led to significant neuroscientific findings within the last two decades, eventually making impact in the clinics. Neuro-oncology can benefit immensely from connectomics in evaluating structural connectivity of brains with tumor for pre- and post-treatment planning, as a tumor connectome along with derived network measures will make it possible to determine the cognitive effects of treatment and quantify the effect of surgery on quality of life. However, generating connectomes in the presence of tumor is a challenging task. Specifically, registration of an atlas to the brain, which is essential in parcellating the brain into regions of interest, fails around the tumor due to mass effect and infiltration related distortions which are not present in the atlas that comes from a healthy brain. We aim to tackle this problem by introducing a novel atlas registration method. METHOD Although tumor deforms the geometrical shape of its surrounding regions, it does not violate the connectivity of displaced cortical voxels to the rest of the brain. Leveraging this fact, we represent the brain as an annotated graph with nodes representing ROIs encoding geometric features of regions and weighted edges representing the connectivity between regions. In encoding the surroundings of the tumor into the graph, we subsample the region into smaller patches to represent the area with multiple nodes. We then calculate many-to-one graph matching between the graphs of a tumor patient and a healthy control to associate surroundings of tumor with healthy ROIs. OUTCOME A tumor connectome showing how the connectivity is morphed around the tumor, which can further be extended to creating connectomes of recurrence. CLINICAL IMPLICATIONS Use of connectomes can revolutionize neuro-oncology by helping surgeons in estimating structural, functional, and behavioral outcomes of resection prior to surgery and in predicting recovery after the surgery, potentially suggesting subject specific treatment plans.
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Logan, Renee. "Neutral Displacement Intravenous Connectors: Evaluating New Technology". Journal of the Association for Vascular Access 18, nr 1 (marzec 2013): 31–36. http://dx.doi.org/10.1016/j.java.2012.12.004.
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Background: The University Hospital of Northern British Columbia (UHNBC) utilized an opaque positive displacement intravenous (IV) line connector in 2011 and for several years previously. With concerns generated in the United States surrounding positive displacement and the potential increased risk for infection, as well as the training requirements related to ensuring that a proper clamping sequence was followed, a neutral displacement IV connector was implemented in October 2011. Methods: Catheter-related blood stream infections and catheter occlusions were monitored at UHNBC for 4 months before (June through September 2011) and 4 months after (November 2011 through February 2012) the implementation of the neutral displacement IV connector by the Parenteral Services nursing team. A staff survey was conducted that reviewed the satisfaction with the newly implemented IV connector. Results: The results of tracking catheter occlusions with a neutral displacement IV connector showed an average of 4.04 occlusions that required tissue plasminogen activator per 1,000 catheter days, compared with 5.47 occlusions that required tissue plasminogen activator per 1,000 catheter days with the positive displacement IV connector. During the evaluation period there was a 26% decrease in catheter occlusions with the implementation of the neutral displacement IV connector. Blood stream infection rates remained at zero for the entire evaluation with both displacement types of IV connectors. Nursing staff members were satisfied with the newly implemented IV connector. Conclusions: UHNBC will continue to utilize the neutral displacement IV connector hospital-wide, and continues to monitor both catheter occlusions and catheter-related blood stream infections. Following UHNBC, facilities in the rest of Northern Health have implemented the neutral displacement IV connector.
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HA, Chunghun, Hong-Bae JUN i Changsoo OK. "Probabilistic evaluation approach for electrical connector mating: An empirical study on automotive electronic connectors". Journal of Advanced Mechanical Design, Systems, and Manufacturing 11, nr 5 (2017): JAMDSM0064. http://dx.doi.org/10.1299/jamdsm.2017jamdsm0064.
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Kolmer, Philipp, Abhay Shukla i Jian Song. "Methods of Material and Surface Analysis for the Evaluation of Failure Modes for Electrical Connectors". Technologies 10, nr 6 (29.11.2022): 124. http://dx.doi.org/10.3390/technologies10060124.
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The development of autonomous vehicles and the integration of new information and communication technologies are making the reliability of electrical systems and components in modern vehicles increasingly important. Electrical connectors are a crucial component in an electrical on-board system. They are exposed to a wide variety of influences by the environment and operating conditions. Thus, the degradation of electrical connectors can occur. Material and surface analysis methods are the tools used to analyze the degradation mechanisms in connectors after lifetime tests, as well as in field operations. Within the framework of this study, a wide variety of methods from the analytical scope are presented and discussed. The connector surfaces degraded by different failure mechanisms are analyzed using various material and surface analysis methods. The quality and the nature of the analyses results obtained from various analysis methods are compared. Also, this study deals with the benefits and limitations, as well as the effort and the specific challenges of different material and surface analytical methods for the evaluation of failure mechanisms from the point of view of a material and surface analyst.
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Bourdine, A., i S. Pashin. "Method for Estimation of Reflection on Fiber Optic Connection Based on Analysis of Images of End Surfaces of Ferrule Connectors". Proceedings of Telecommunication Universities 6, nr 4 (grudzień 2020): 16–27. http://dx.doi.org/10.31854/1813-324x-2020-6-4-16-27.
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This work presents an alternative method for evaluating the reflection coefficient at a detachable connection of single-mode optical fibers based on the results of the analysis of images of the contaminated end surface of the ferrule of a pair of connectors of the studied joint, obtained with a standard field set of video diagnostics of the state of fiber-optic connectors. The results of experimental verification of the proposed method are presented, which have demonstrated the potential of its use in practical applications of "contactless" determination of the reflection coefficient on a fiber-optic connector.
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Liu, Xiaobo, Su Yang i Zhengxian Liu. "Predicting Fluid Intelligence via Naturalistic Functional Connectivity Using Weighted Ensemble Model and Network Analysis". NeuroSci 2, nr 4 (17.12.2021): 427–42. http://dx.doi.org/10.3390/neurosci2040032.
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Objectives: Functional connectivity triggered by naturalistic stimuli (e.g., movie clips), coupled with machine learning techniques provide great insight in exploring brain functions such as fluid intelligence. However, functional connectivity is multi-layered while traditional machine learning is based on individual model, which is not only limited in performance, but also fails to extract multi-dimensional and multi-layered information from the brain network. Methods: In this study, inspired by multi-layer brain network structure, we propose a new method, namely weighted ensemble model and network analysis, which combines machine learning and graph theory for improved fluid intelligence prediction. Firstly, functional connectivity analysis and graphical theory were jointly employed. The functional connectivity and graphical indices computed using the preprocessed fMRI data were then all fed into an auto-encoder parallelly for automatic feature extraction to predict the fluid intelligence. In order to improve the performance, tree regression and ridge regression models were stacked and fused automatically with weighted values. Finally, layers of auto-encoder were visualized to better illustrate the connectome patterns, followed by the evaluation of the performance to justify the mechanism of brain functions. Results: Our proposed method achieved the best performance with a 3.85 mean absolute deviation, 0.66 correlation coefficient and 0.42 R-squared coefficient; this model outperformed other state-of-the-art methods. It is also worth noting that the optimization of the biological pattern extraction was automated though the auto-encoder algorithm. Conclusion: The proposed method outperforms the state-of-the-art reports, also is able to effectively capture the biological patterns of functional connectivity during a naturalistic movie state for potential clinical explorations.
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Li, Zhonghua. "Analysis of Changes in Brain Region and Connectomics in the Acute Stage of Sudden Sensorineural Hearing Loss in the Resting State via Functional Magnetic Resonance Imaging". Concepts in Magnetic Resonance Part A 2023 (25.02.2023): 1–8. http://dx.doi.org/10.1155/2023/7007209.
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To explore the functional changes in the whole brain network in patients with sudden sensorineural hearing loss (SHL) at the acute stage from functional magnetic resonance imaging (fMRI) imaging evaluation results, 80 patients with sudden right SHL were selected as subjects (patient group). In addition, 40 healthy volunteers who underwent physical examination in the hospital during the same period were recruited as a control group. fMRI imaging was performed to analyze functional parameters and core nodes of the whole brain network. It was found that at all thresholds, the fMRI parameters Cp and Lp of the patient group were dramatically superior to those of the control group. The fMRI parameter Eglobal of the patient group was substantially lower than that of the control group ( P < 0.05 ). At most of the thresholds, the fMRI parameter λ in patients was dramatically superior to that in the control group ( P < 0.05 ). There were ten specific network core nodes in patients, including the right parahippocampal gyrus, right supra-occipital gyrus, left suboccipital gyrus, right fusiform gyrus, right parietal lobule, right subparietal lobule, right superior temporal gyrus, left superior marginal gyrus, and right superior temporal gyrus. In summary, the whole brains of patients with sudden SHL still had small-world attributes, but some characteristics of the brain network had changed, and there was a trend of transformation to a regular network. The connection between the auditory brain area and the functional areas related to language and vision was weakened, and the distribution of core nodes changed. This study provides a reference basis for exploring the changes in local brain and connectome levels in patients with sudden sensorineural hearing loss in the acute phase based on resting-state fMRI.
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Szultka, Seweryn, Stanislaw Czapp, Adam Tomaszewski i Hayat Ullah. "Evaluation of Fire Hazard in Electrical Installations Due to Unfavorable Ambient Thermal Conditions". Fire 6, nr 2 (20.01.2023): 41. http://dx.doi.org/10.3390/fire6020041.
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Evaluation of fire hazard caused by electrical installations is a difficult and important topic, and it limits the possibility of loss of life or health of people, as well as the occurrence of significant property damage. In particular, this hazard was caused by power cables and especially photovoltaic (PV) installations. The authors proved that power cables directly exposed to strong solar radiation are likely to exceed maximum permissible temperature in unfavorable ambient conditions. Overheated and damaged cable insulation can be a source of electric shock and a strong leakage current causing fire. In the case of typical PV connectors (MC4 connectors), the main problem is poor contact at the connections of the PV cables. A poor connection can even cause the connector to melt, as shown in this study. In the paper, the authors present a computer simulation regarding critical thermal points of electrical installations, in particular, of the PV type. It may be an indication of what should be paid attention to when designing and implementing such installations. This is important for the safety of people and buildings.
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Ding, Wangfei, Abdullah Alharbi, Ahmad Almadhor, Payam Rahnamayiezekavat, Masoud Mohammadi i Maria Rashidi. "Evaluation of the Performance of a Composite Profile at Elevated Temperatures Using Finite Element and Hybrid Artificial Intelligence Techniques". Materials 15, nr 4 (14.02.2022): 1402. http://dx.doi.org/10.3390/ma15041402.
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It is very important to keep structures and constructional elements in service during and after exposure to elevated temperatures. Investigation of the structural behaviour of different components and structures at elevated temperatures is an approach to manipulate the serviceability of the structures during heat exposure. Channel connectors are widely used shear connectors not only for their appealing mechanical properties but also for their workability and cost-effective nature. In this study, a finite element (FE) evaluation was performed on an authentic composite model, and the behaviour of the channel shear connector at elevated temperature was examined. Furthermore, a novel hybrid intelligence algorithm based on a feature-selection trait with the incorporation of particle swarm optimization (PSO) and multi-layer perceptron (MLP) algorithms has been developed to predict the slip response of the channel. The hybrid intelligence algorithm that uses artificial neural networks is performed on derived data from the FE study. Finally, the obtained numerical results are compared with extreme learning machine (ELM) and radial basis function (RBF) results. The MLP-PSO represented dramatically accurate results for slip value prediction at elevated temperatures. The results proved the active presence of the channels, especially to improve the stiffness and loading capacity of the composite beam. Although the height enhances the ductility, stiffness is significantly reduced at elevated temperatures. According to the results, temperature, failure load, the height of connector and concrete block strength are the key governing parameters for composite floor design against high temperatures.
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Peng, Kai, Laijun Liu, Fangwen Wu, Song Lei, Jincheng Cao, Xiangyan Fan i Xuan Wang. "Experimental and Numerical Evaluation of the Performance of Perfobond Leiste Shear Connectors in Steel–SFRCC Composite Beams". Materials 15, nr 20 (17.10.2022): 7237. http://dx.doi.org/10.3390/ma15207237.
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The difference between the shear performances of Perfobond Leiste (PBL) shear connectors embedded in steel fiber-reinforced cementitious composite (SFRCC) structure and normal strength concrete (NC) structure was investigated by push-out tests and finite element (FE) simulations. Push-out tests were carried out on nine steel-SFRCC specimens and nine steel-NC specimens. The mechanical behavior of the PBL shear connector was examined according to the failure modes, load-slip curves, and strain distribution laws of the push-out specimens. Experimental results revealed that the extension of cracks in SFRCC was hindered by steel fibers, and the number and width of cracks in SFRCC were smaller than those in NC. The failure mode of the steel-SFRCC specimens and the single-hole steel-NC specimens was the shear failure of the penetrating reinforcement, whereas that of the multi-hole NC specimens was concrete slab cracking. The ultimate shear bearing capacity of PBL shear connectors in the steel-SFRCC specimens was 47.8% greater than that in the steel-NC specimens. Furthermore, an FE model verified by the test results was established to conduct parametric analyses. It was found that the hole diameter and thickness of the steel plate and the yield strength of the penetrating rebar greatly affected the shear bearing capacity of PBL shear connectors. Finally, based on the experimental and FE simulation results, an expression for calculating the ultimate shear bearing capacity of PBL shear connectors in the steel-SFRCC composite structure was developed by considering the bearing effects of concrete dowels, penetrating rebars, and end parts.
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Du, Yong Ying, i Zhi Li Sun. "Research on Temperature Stress for Contacts Reliability of Electric Connector". Advanced Materials Research 945-949 (czerwiec 2014): 1082–85. http://dx.doi.org/10.4028/www.scientific.net/amr.945-949.1082.
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Temperature induced degradation is a widely recognized failure phenomenon.However, the basic mechanisms that control the onset and progression of such behavior are not well understood and are a topic of considerable interest in the electrical connector community. In this paper, the simulation analysis of temperature field on this topic are described. The distribution graph of temperature field for the electrical connectors and the highest temperature of the surface of electrical connector was achieved by analyzing a single blade/receptacle contact pair FEA model. A mathematical model was developed that related the early stage temperature levels for the connectors.Additionally, the thermal deformation caused by the temperature had little effect on the contact stress based on temperature - structure coupling field analysis for the electrical connector, the impact of temperature on the electrical connector was mainly reflected in the rate of oxidation of the metal surface. The failure physical process of the electric connector was drawn under temperature stress through the model and theory analysis for the electrical connector , and reliability growth program of the electrical connector was achieved under the temperature influence. The same transfer functions for one type of contact pair were obtained from the simulation, and the results showed that for this limited system, finite element modeling and analysis have great potential for evaluating the influence of design variations on degradation behavior.