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# tensor

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#1
Genxia He, Junchao Qian
It was known that Spinal cord injury (SCI) leads to neuronal cell death, axonal damage and demyelination, and often results in severe functional loss. Noninvasive imaging of axonal integrity may hold great importance in clinic. This study evaluated the role of phase imaging in detection of axonal integrity of cranial corticospinal tract after spinal cord injury. Quantitative MR phase imaging and diffusion tensor imaging were performed on a group of rats prior to and after spinal cord injury at 9.4 T in this study...
May 23, 2017: Microscopy Research and Technique
#2
Mingze Xu, Yi Zhang, Karen M von Deneen, Huaiqiu Zhu, Jia-Hong Gao
Prader-Willi syndrome (PWS) is a genetic imprinting disorder that is mainly characterized by hyperphagia and childhood obesity. Previous neuroimaging studies revealed that there is a significant difference in brain activation patterns between obese children with and without PWS. However, whether there are differences in the brain structure of obese children with and without PWS remains elusive. In the current study, we used T1-weighted and diffusion tensor magnetic resonance imaging to investigate alterations in the brain structure, such as the cortical volume and white matter integrity, in relation to this eating disorder in 12 children with PWS, 18 obese children without PWS (OB) and 18 healthy controls...
May 23, 2017: Human Brain Mapping
#3
Thiago Junqueira R Rezende, Alberto Rolim M Martinez, Ingrid Faber, Karen Girotto, José Luiz Pedroso, Orlando G Barsottini, Iscia Lopes-Cendes, Fernando Cendes, Andreia V Faria, Marcondes C França
INTRODUCTION: Friedreich's ataxia (FRDA) is the most common autosomal-recessive ataxia worldwide. It is characterized by early onset, sensory abnormalities, and slowly progressive ataxia. However, some individuals manifest the disease after the age of 25 years and are classified as late-onset FRDA (LOFA). Therefore, we propose a transversal multimodal MRI-based study to investigate which anatomical substrates are involved in classical (cFRDA) and LOFA. METHODS: We enrolled 36 patients (13 with LOFA) and 29 healthy controls...
May 23, 2017: Human Brain Mapping
#4
John Darrell Van Horn, Andrei Irimia, Carinna M Torgerson, Avnish Bhattrai, Zachary Jacokes, Paul M Vespa
In this report, we present a case study involving an older, female patient with a history of pediatric traumatic brain injury (TBI). Magnetic resonance imaging and diffusion tensor imaging volumes were acquired from the volunteer in question, her brain volumetrics and morphometrics were extracted, and these were then systematically compared against corresponding metrics obtained from a large sample of older healthy control (HC) subjects as well as from subjects in various stages of mild cognitive impairment (MCI) and Alzheimer disease (AD)...
May 20, 2017: Journal of Neuroscience Research
#5
Can Zhao, Wei Song, Jia-Sheng Rao, Wen Zhao, Rui-Han Wei, Xia Zhou, Peng-Yu Tian, Zhao-Yang Yang, Xiao-Guang Li
BACKGROUND: Spinal cord injury (SCI) causes loss of locomotor functions. Nowadays, the relationship between the residual locomotion after SCI and the diffusion tensor tractography (DTT) results still remains unclear. METHODS: Four rhesus monkeys were suffered thoracic cord hemisection. Kinematic evaluation and DTT were performed prior- and post-SCI (6 and 12 weeks). The longitudinal changes of gait parameters and the DTT parameters were analyzed for the injury-contralateral hindlimb...
May 23, 2017: Journal of Medical Primatology
#6
Taras Leonidovych Petrenko, V Bryksa
At present nitrogen-vacancy (NV) complex in diamond is the most promising defect for application in the area of quantum computing. This provides a stimulus for extensive search of another defects in semiconductors with similar properties. Recently it was shown that N$_{C}$V$_{Si}$ defect complex in SiC is perspective for this goal as well. In the present work we perform comparative \textit{ab initio} studies of NV complexes in diamond and 3\textit{C}-SiC. We focus both on radiospectroscopic characterization of these defects and on calculation of equilibrium concentration of complexes in irradiated crystals...
May 25, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
#7
Alexander A Pavlov, Svetlana A Savkina, Alexander S Belov, Yulia V Nelyubina, Nikolay N Efimov, Yan Z Voloshin, Valentin V Novikov
High magnetic anisotropy is a key property of paramagnetic shift tags, which are mostly studied by NMR spectroscopy, and of single molecule magnets, for which magnetometry is usually used. We successfully employed both these methods in analyzing magnetic properties of a series of transition metal complexes, the so-called clathrochelates. A cobalt complex was found to be both a promising paramagnetic shift tag and a single molecule magnet because of it having large axial magnetic susceptibility tensor anisotropy at room temperature (22...
May 25, 2017: Inorganic Chemistry
#8
John O Glass, Robert J Ogg, Jung W Hyun, Julie H Harreld, Jane E Schreiber, Yimei Li, Amar J Gajjar, Wilburn E Reddick
Background.: Treatment of pediatric medulloblastoma is associated with known neurocognitive deficits that we hypothesize are caused by microstructural damage to frontal white matter (WM). Methods.: Longitudinal MRI examinations were collected from baseline (after surgery but before therapy) to 36 months in 146 patients and at 3 time points in 72 controls. Regional analyses of frontal WM volume and diffusion tensor imaging metrics were performed and verified with tract-based spatial statistics...
May 25, 2017: Neuro-oncology
#9
Sujoy Kumar Biswas, Peyman Milanfar
Pedestrian detection in thermal infrared images poses unique challenges because of the low resolution and noisy nature of the image. Here we propose a mid-level attribute in the form of the multidimensional template, or tensor, using Local Steering Kernel (LSK) as low-level descriptors for detecting pedestrians in far infrared images. LSK is specifically designed to deal with intrinsic image noise and pixel level uncertainty by capturing local image geometry succinctly instead of collecting local orientation statistics (e...
May 18, 2017: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
#10
Alessandro Arrigo, Michele Gaeta, Alessandro Calamuneri, Enricomaria Mormina, Silvia Marino, Francesco Stagno d'Alcontres, Marcello Longo, Francesca Granata
In this study we described a case of lipofibromatous hamartoma involving the median nerve. We adopted diffusion tensor imaging and constrained spherical deconvolution-based tractography to reconstruct the affected median nerve. Moreover, we extracted diffusion-based parameters reflecting axonal integrity loss of median nerve fibres. Our data showed that constrained spherical deconvolution-based tractography outperformed the diffusion tensor imaging-based method, allowing the detection of the entire median nerve, including its branches, thus offering a robust method to investigate the involvement of the median nerve in pathological conditions...
#11
Woo Kyoung Yoo, Yoon Ghil Park, Young Chul Choi, Sun Mi Kim
PURPOSE: Myotonic dystrophy type 1 (DM1) is characterized by progressive muscular weakness with symptoms caused by involvement of the brain. The aim of this study was to delineate global changes in cortical thickness and white matter integrity in patients with DM1, compared to age-matched healthy controls, and in brain areas highly correlated with CTG repeat size. MATERIALS AND METHODS: Cortical thickness and white matter integrity were compared in nine adult DM1 patients and age matched healthy controls using T1-weighted and diffusion tensor imaging...
July 2017: Yonsei Medical Journal
#12
ChunYan Luo, Wei Song, Qin Chen, Jing Yang, QiYong Gong, Hui-Fang Shang
PURPOSE: Resting tremor is one of the cardinal motor features of Parkinson's disease (PD). Several lines of evidence suggest resting tremor may have different underlying pathophysiological processes from those of bradykinesia and rigidity. The current study aims to identify white matter microstructural abnormalities associated with resting tremor in PD. METHODS: We recruited 60 patients with PD (30 with tremor-dominant PD and 30 with nontremor-dominant PD) and 26 normal controls...
#13
Fan Fan, Dandan Feng, Rui Wang, Qiang Zhang, Haijun Niu
This paper proposed to take advantages of resonant ultrasound spectroscopy (RUS) to measure the mechanical properties of human dentin specimen. The resonant spectroscopy of the dentin specimen was obtained between the frequency bands 155 and 575 kHz, and resonant frequencies were extracted by linear predictive filter and then by Levenberg-Marquardt method. By inverse problem approach, 13 experimental resonant frequencies progressively matched to the first 30 orders of theoretical resonant frequencies calculated by Lagrangian variational method...
2017: BioMed Research International
#14
Francesca Granata, Sergio Racchiusa, Enricomaria Mormina, Valeria Barresi, Giada Garufi, Giovanni Grasso, Francesco Maria Salpietro, Marcello Longo, Concetta Alafaci
BACKGROUND: Intramedullary spinal ependymoma is a tumor, hardly characterizable with conventional magnetic resonance (MR) imaging only. MR diffusion tensor imaging (DTI) with three-dimensional fiber-tracking reconstructions allows the evaluation of the relationship between neoplasm and white matter fiber tracts, being a powerful tool in presurgical planning. We present DTI findings in a case of a young female with an extensive cervicothoracic spinal ependymoma. CASE DESCRIPTION: The patient complained of a 2-month history of acute urinary retention, weakness and numbness on the lower limbs and the upper left limb...
2017: Surgical Neurology International
#15
Haofei Liu, Wei Sun
Objective stress rates are often used in commercial finite element (FE) programs. However, deriving a consistent tangent modulus tensor (also known as elasticity tensor or material Jacobian) associated with the objective stress rates is challenging when complex material models are utilized. In this paper, an approximation method for the tangent modulus tensor associated with the Green-Naghdi rate of the Kirchhoff stress is employed to simplify the evaluation process. The effectiveness of the approach is demonstrated through the implementation of two user-defined fiber-reinforced hyperelastic material models...
May 24, 2017: Journal of Biomechanical Engineering
#16
Bingcheng Luo, Xiaohui Wang, Enke Tian, Hongzhou Song, Hongxian Wang, Longtu Li
A novel lead-free (1-x) CaTiO3-xBiScO3 linear dielectric ceramic with enhanced energy storage density was fabricated. With the composition of BiScO3 increasing, the dielectric constant of (1-x)CaTiO3-xBiScO3 ceramics firstly increased and then decreased after the composition x>0.1, while the dielectric loss decreased firstly and increased. For the composition x=0.1, the polarization was increased into 12.36 μC/cm2, 4.6 times higher than that of the pure CaTiO3. The energy density of 0.9 CaTiO3-0.1 BiScO3 ceramic was 1...
May 24, 2017: ACS Applied Materials & Interfaces
#17
Torin J A Glass, Vann Chau, Jane Gardiner, Justin Foong, Jillian Vinall, Jill G Zwicker, Ruth E Grunau, Anne Synnes, Kenneth J Poskitt, Steven P Miller
OBJECTIVE: To determine whether severe retinopathy of prematurity (ROP) is associated with (1) abnormal white matter maturation and (2) neurodevelopmental outcomes at 18 months' corrected age (CA) compared with neonates without severe ROP. DESIGN: We conducted a prospective longitudinal cohort of extremely preterm neonates born 24-28 weeks' gestational age recruited between 2006 and 2013 with brain MRIs obtained both early in life and at term-equivalent age. Severe ROP was defined as ROP treated with retinal laser photocoagulation...
May 23, 2017: Archives of Disease in Childhood. Fetal and Neonatal Edition
#18
Marcello Sega, Balázs Fábián, Pal Jedlovszky
Surface tension, the tendency of fluid interfaces to behave elastically and minimize their surface, is routinely calculated as the difference between the lateral and normal components of the pressure or, invoking isotropy in momentum space, of the virial tensor. Here we show that the anisotropy of the kinetic energy tensor close to a liquid/vapour interface can be responsible for a large part of its surface tension (about 15 % for water, independently on temperature).
May 23, 2017: Journal of Physical Chemistry Letters
#19
Sebastian Vellmer, Aram S Tonoyan, Dieter Suter, Igor N Pronin, Ivan I Maximov
Diffusion magnetic resonance imaging (dMRI) is a powerful tool in clinical applications, in particular, in oncology screening. dMRI demonstrated its benefit and efficiency in the localisation and detection of different types of human brain tumours. Clinical dMRI data suffer from multiple artefacts such as motion and eddy-current distortions, contamination by noise, outliers etc. In order to increase the image quality of the derived diffusion scalar metrics and the accuracy of the subsequent data analysis, various pre-processing approaches are actively developed and used...
May 19, 2017: Zeitschrift Für Medizinische Physik
#20
Agustin M Cardenas, Joelle E Sarlls, Justin Y Kwan, Devin Bageac, Zachary S Gala, Laura E Danielian, Abhik Ray-Chaudhury, Hao-Wei Wang, Karla L Miller, Sean Foxley, Saad Jbabdi, Robert C Welsh, Mary Kay Floeter
OBJECTIVES: The goal of this study was to better understand the changes in tissue microstructure that underlie white matter diffusion changes in ALS patients. METHODS: Diffusion tensor imaging was carried out in postmortem brains of 4 ALS patients and two subjects without neurological disease on a 7 T MRI scanner using steady-state free precession sequences. Fractional anisotropy (FA) was measured in the genu, body, and splenium of the corpus callosum in formalin-fixed hemispheres...
2017: NeuroImage: Clinical
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