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https://www.readbyqxmd.com/read/28338911/new-horizons-in-hospital-acquired-pneumonia-in-older-people
#1
Victoria Ewan, Thomas Hellyer, Julia Newton, John Simpson
Approximately 1.5% of hospital patients develop hospital acquired pneumonia. Aspiration is the major risk factor for pneumonia and is associated with reduced ability to mechanically clear respiratory pathogens into the stomach. Currently non-invasive methods of diagnosing hospital acquired pneumonia are less robust than invasive methods, and lead to over-diagnosis. Accurate diagnosis is key to surveillance, prevention and treatment of HAP, and also to improving outcomes; newer imaging modalities such as phase contrast X-ray imaging and nanoparticle enhanced magnetic resonance imaging may help...
February 27, 2017: Age and Ageing
https://www.readbyqxmd.com/read/28336427/high-resolution-anatomical-and-quantitative-mri-of-the-entire-human-occipital-lobe-ex-vivo-at-9-4t
#2
S Sengupta, F J Fritz, R L Harms, S Hildebrand, D H Y Tse, B A Poser, R Goebel, A Roebroeck
Several magnetic resonance imaging (MRI) contrasts are sensitive to myelin content in gray matter in vivo which has ignited ambitions of MRI-based in vivo cortical histology. Ultra-high field (UHF) MRI, at fields of 7T and beyond, is crucial to provide the resolution and contrast needed to sample contrasts over the depth of the cortex and get closer to layer resolved imaging. Ex vivo MRI of human post mortem samples is an important stepping stone to investigate MRI contrast in the cortex, validate it against histology techniques applied in situ to the same tissue, and investigate the resolutions needed to translate ex vivo findings to in vivo UHF MRI...
March 20, 2017: NeuroImage
https://www.readbyqxmd.com/read/28334577/on-the-achievable-field-sensitivity-of-a-segmented-annular-detector-for-differential-phase-contrast-measurements
#3
Felix Schwarzhuber, Peter Melzl, Josef Zweck
Differential phase contrast microscopy measures minute deflections of the electron probe due to electric and/or magnetic fields, using a position sensitive device. Although recently, pixelated detectors have become available which also serve as a position sensitive device, the most frequently used detector is a four-segmented annular semiconducting detector ring (or variations thereof), where the difference signals of opposing detector elements represent the components of the deflection vector. This deflection vector can be used directly to quantitatively determine the deflecting field, provided the specimen's thickness is known...
March 4, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/28329054/whole-heart-detailed-and-quantitative-anatomy-myofibre-structure-and-vasculature-from-x-ray-phase-contrast-synchrotron-radiation-based-micro-computed-tomography
#4
Anna Gonzalez-Tendero, Chong Zhang, Vedrana Balicevic, Rubén Cárdenes, Sven Loncaric, Constantine Butakoff, Bruno Paun, Anne Bonnin, Patricia Garcia-Cañadilla, Emma Muñoz-Moreno, Eduard Gratacós, Fatima Crispi, Bart Bijnens
Background: While individual cardiac myocytes only have a limited ability to shorten, the heart efficiently pumps a large volume-fraction thanks to a cell organization in a complex 3D fibre structure. Subclinical subtle cardiac structural remodelling is often present before symptoms arise. Understanding and early detection of these subtle changes is crucial for diagnosis and prevention. Additionally, personalized computational modelling requires knowledge on the multi-scale structure of the whole heart and vessels...
March 15, 2017: European Heart Journal Cardiovascular Imaging
https://www.readbyqxmd.com/read/28325443/vascular-segmentation-of-head-phase-contrast-magnetic-resonance-angiograms-using-grayscale-and-shape-features
#5
Ruoxiu Xiao, Hui Ding, Fangwen Zhai, Tong Zhao, Wenjing Zhou, Guangzhi Wang
BACKGROUND AND OBJECTIVE: In neurosurgery planning, vascular structures must be predetermined, which can guarantee the security of the operation carried out in the case of avoiding blood vessels. In this paper, an automatic algorithm of vascular segmentation, which combined the grayscale and shape features of the blood vessels, is proposed to extract 3D vascular structures from head phase-contrast magnetic resonance angiography dataset. METHODS: First, a cost function of mis-segmentation is introduced on the basis of traditional Bayesian statistical classification, and the blood vessel of weak grayscale that tended to be misclassified into background will be preserved...
April 2017: Computer Methods and Programs in Biomedicine
https://www.readbyqxmd.com/read/28324943/overcoming-spatio-temporal-limitations-using-dynamically-scaled-in-vitro-pc-mri-a-flow-field-comparison-to-true-scale-computer-simulations-of-idealized-stented-and-patient-specific-left-main-bifurcations
#6
Susann Beier, John Ormiston, Mark Webster, John Cater, Stuart Norris, Pau Medrano-Gracia, Alistair Young, Kathleen Gilbert, Brett Cowan
The majority of patients with angina or heart failure have coronary artery disease. Left main bifurcations are particularly susceptible to pathological narrowing. Flow is a major factor of atheroma development, but limitations in imaging technology such as spatio-temporal resolution, signal-to-noise ratio (SNRv), and imaging artefacts prevent in vivo investigations. Computational fluid dynamics (CFD) modelling is a common numerical approach to study flow, but it requires a cautious and rigorous application for meaningful results...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28323634/effect-of-laser-pulse-propagation-on-ultrafast-magnetization-dynamics-in-a-birefringent-medium
#7
J A de Jong, A M Kalashnikova, R V Pisarev, A M Balbashov, A V Kimel, A Kirilyuk, Th Rasing
Light propagation effects can strongly influence the excitation and the detection of laser-induced magnetization dynamics. We investigated experimentally and analytically the effects of crystallographic linear birefringence on the excitation and detection of ultrafast magnetization dynamics in the rare-earth orthoferrites (Sm0.5Pr0.5)FeO3 and (Sm0.55Tb0.45)FeO3, which possess weak and strong linear birefringence, respectively. Our finding is that the effect of linear birefringence on the result of a magneto-optical pump-probe experiment strongly depends on the mechanism of excitation...
April 26, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28321684/left-ventricular-flow-propagation-velocity-measurement-is-it-cast-in-stone
#8
Bee Ting Chan, Hak Koon Yeoh, Yih Miin Liew, Yang Faridah Abdul Aziz, Ganiga Srinivasaiah Sridhar, Christian Hamilton-Craig, David Platts, Einly Lim
This study aims to investigate the measurement of left ventricular flow propagation velocity, V p, using phase contrast magnetic resonance imaging and to assess the discrepancies resulting from inflow jet direction and individual left ventricular size. Three V p measuring techniques, namely non-adaptive (NA), adaptive positions (AP) and adaptive vectors (AV) method, were suggested and compared. We performed the comparison on nine healthy volunteers and nine post-infarct patients at four measurement positions, respectively, at one-third, one-half, two-thirds and the conventional 4 cm distances from the mitral valve leaflet into the left ventricle...
March 20, 2017: Medical & Biological Engineering & Computing
https://www.readbyqxmd.com/read/28317480/novel-insights-into-complex-cardiovascular-pathologies-using-4d-flow-analysis-by-cardiovascular-magnetic-resonance-imaging
#9
Adam James Lewandowski, Betty Raman, Rajarshi Banerjee, Matteo Milanesi
BACKGROUND: It is essential that we are able to assess variations in blood flow in order to fully understand cardiovascular function in disease pathologies and for identification of individuals at long-term risk of cardiovascular disease development. Qualitative and quantitative assessments of blood flow by imaging modalities have been limited, and much of the accurate quantification has relied on invasive measures. METHODS: This review discusses how four-dimensional velocity cardiovascular magnetic resonance (4D flow CMR) offers increasing potential for the non-invasive assessment of blood flow in the heart and major blood vessels such as the aorta...
March 17, 2017: Current Pharmaceutical Design
https://www.readbyqxmd.com/read/28301100/comparison-of-mr-flow-quantification-in-peripheral-and-main-pulmonary-arteries-in-patients-after-right-ventricular-outflow-tract-surgery-a-retrospective-study
#10
Tobias Rutz, Christian Meierhofer, Susanne Naumann, Stefan Martinoff, Peter Ewert, Heiko C Stern, Sohrab Fratz
PURPOSE: To compare the quantification of pulmonary stroke volume (SV) by phase contrast magnetic resonance (PC-MR) in the main pulmonary artery (MPA) to the sum of SVs in both peripheral pulmonary arteries (PPA) in different right ventricular (RV) outflow pathologies. MATERIALS AND METHODS: Pulmonary SV was determined by PC-MR in the MPA and the PPA in healthy individuals (H, n = 54), patients after correction for tetralogy of Fallot with significant pulmonary regurgitation and without pulmonary or RV outflow tract stenosis (PR, n = 50), and in patients with RV outflow tract or pulmonary valve stenosis (PS, n = 50)...
March 16, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28296356/positional-changes-of-the-ocular-organs-during-craniofacial-development
#11
Miho Osaka, Aoi Ishikawa, Shigehito Yamada, Chigako Uwabe, Hirohiko Imai, Tetsuya Matsuda, Akio Yoneyama, Tohoru Takeda, Tetsuya Takakuwa
The present study aimed to describe the positional changes of the ocular organs during craniofacial development; moreover, we examined the relationships among the ocular organs and other internal structures. To do this, we traced the positions of the ocular organs in 56 human early fetal samples at different stages of development using high-resolution magnetic resonance imaging and phase-contrast X-ray computed tomography. The eyes were located on the lateral side in the ventral view at Carnegie stage (CS) 16, and then changed their positions medially during development...
March 13, 2017: Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology
https://www.readbyqxmd.com/read/28295788/creating-hemodynamic-atlases-of-cardiac-4d-flow-mri
#12
Merih Cibis, Mariana Bustamante, Jonatan Eriksson, Carl-Johan Carlhäll, Tino Ebbers
PURPOSE: Hemodynamic atlases can add to the pathophysiological understanding of cardiac diseases. This study proposes a method to create hemodynamic atlases using 4D Flow magnetic resonance imaging (MRI). The method is demonstrated for kinetic energy (KE) and helicity density (Hd ). MATERIALS AND METHODS: Thirteen healthy subjects underwent 4D Flow MRI at 3T. Phase-contrast magnetic resonance cardioangiographies (PC-MRCAs) and an average heart were created and segmented...
March 13, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28291018/magnetic-excitations-in-the-normal-and-nematic-phases-of-iron-pnictides
#13
Haiyang Zhang, Ning Xu
In this paper, we study theoretically the behaviors of the magnetic excitations(MEs) in the normal and nematic phases of iron pnictides. The normal state MEs exhibit commensurability to diamond and to square-like structure transition with the increase of energy. This structure transition persists in the spin and orbital scenarios of nematic phases, although the MEs show anisotropic behaviors due to the C4 symmetry breaking induced by the nematic orders. The MEs exhibit distinct energy evolution behaviors between the spin and orbital scenarios of nematicity...
March 14, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28287748/colossal-terahertz-magnetoresistance-at-room-temperature-in-epitaxial-la0-7sr0-3mno3-nanocomposites-and-single-phase-thin-films
#14
J Lloyd-Hughes, Connor Mosley, Samuel Jones, Martin R Lees, Aiping Chen, Quanxi Jia, Eun Mi Choi, Judith L MacManus Driscoll
Colossal magnetoresistance (CMR) is demonstrated at terahertz (THz) frequencies by using terahertz time-domain magnetospectroscopy to examine nanocolumns and planar thin films of La0.7Sr0.3MnO3. At the metal-insulator transition the THz conductivity of the nanocolumn film was dramatically enhanced by the application of a magnetic field, creating a non-Drude conductivity that increased with frequency. The colossal magnetoresistance at 1.0THz is -99.9% at the Curie temperature (room temperature), far exceeding the dc magnetoresistance...
March 13, 2017: Nano Letters
https://www.readbyqxmd.com/read/28287604/in-situ-visualization-of-the-phase-behavior-of-oil-samples-under-refinery-process-conditions
#15
Cedric Laborde-Boutet, William C McCaffrey
To help address production issues in refineries caused by the fouling of process units and lines, we have developed a setup as well as a method to visualize the behavior of petroleum samples under process conditions. The experimental setup relies on a custom-built micro-reactor fitted with a sapphire window at the bottom, which is placed over the objective of an inverted microscope equipped with a cross-polarizer module. Using reflection microscopy enables the visualization of opaque samples, such as petroleum vacuum residues, or asphaltenes...
February 21, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28286597/extending-the-lifetime-of-hyperpolarized-propane-gas-through-reversible-dissolution
#16
Dudari B Burueva, Alexey S Romanov, Oleg G Salnikov, Vladimir V Zhivonitko, Yu-Wen Chen, Danila A Barskiy, Eduard Y Chekmenev, Dennis W Hwang, Kirill V Kovtunov, Igor V Koptyug
Hyperpolarized (HP) propane produced by the parahydrogen-induced polarization (PHIP) technique has been recently introduced as a promising contrast agent for functional lung magnetic resonance (MR) imaging. However, its short lifetime due to a spin-lattice relaxation time T1 of less than 1 s in the gas phase is a significant translational challenge for its potential biomedical applications. The previously demonstrated approach for extending the lifetime of the HP propane state through long-lived spin states allows the HP propane lifetime to be increased by a factor of ∼3...
March 2, 2017: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
https://www.readbyqxmd.com/read/28282179/temperature-and-magnetic-field-dependence-of-the-internal-and-lattice-structures-of-skyrmions-by-off-axis-electron-holography
#17
K Shibata, A Kovács, N S Kiselev, N Kanazawa, R E Dunin-Borkowski, Y Tokura
The internal and lattice structures of magnetic Skyrmions in B20-type FeGe are investigated using off-axis electron holography. The temperature, magnetic field, and angular dependence of the magnetic moments of individual Skyrmions are analyzed. The internal Skyrmion shape is found to vary with applied magnetic field. In contrast, the inter-Skyrmion distance remains almost unchanged in the lattice phase over the studied range of applied field. The amplitude of the local magnetic moment is found to vary with temperature, while the Skyrmion shape does not change significantly...
February 24, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28281542/observation-of-stable-n%C3%A3-el-skyrmions-in-cobalt-palladium-multilayers-with-lorentz-transmission-electron-microscopy
#18
Shawn D Pollard, Joseph A Garlow, Jiawei Yu, Zhen Wang, Yimei Zhu, Hyunsoo Yang
Néel skyrmions are of high interest due to their potential applications in a variety of spintronic devices, currently accessible in ultrathin heavy metal/ferromagnetic bilayers and multilayers with a strong Dzyaloshinskii-Moriya interaction. Here we report on the direct imaging of chiral spin structures including skyrmions in an exchange-coupled cobalt/palladium multilayer at room temperature with Lorentz transmission electron microscopy, a high-resolution technique previously suggested to exhibit no Néel skyrmion contrast...
March 10, 2017: Nature Communications
https://www.readbyqxmd.com/read/28280686/the-first-week-after-concussion-blood-flow-brain-function-and-white-matter-microstructure
#19
Nathan W Churchill, Michael G Hutchison, Doug Richards, General Leung, Simon J Graham, Tom A Schweizer
Concussion is a major health concern, associated with short-term deficits in physical function, emotion and cognition, along with negative long-term health outcomes. However, we remain in the early stages of characterizing MRI markers of concussion, particularly during the first week post-injury when symptoms are most severe. In this study, 52 varsity athletes were scanned using Magnetic Resonance Imaging (MRI), including 26 athletes with acute concussion (scanned 1-7 days post-injury) and 26 matched control athletes...
2017: NeuroImage: Clinical
https://www.readbyqxmd.com/read/28277551/comparison-of-diffuse-weighted-imaging-and-fluid-attenuation-inversion-recovery-sequences-of-mri-in-brain-multiple-sclerosis-plaques-detection
#20
Reza Nafisi-Moghadam, Abolghasem Rahimdel, Tahereh Shanbehzadeh, Razieh Fallah
OBJECTIVE: Suitable magnetic resonance imaging (MRI) techniques from conventional to new devices can help physicians in diagnosis and follow up of Multiple Sclerosis (MS) patients. The aim of present research was to compare effectiveness of Fluid Attenuation Inversion Recovery (FLAIR) sequence of conventional MRI and Diffuse Weighted Imaging (DWI) sequence as a new technique in detection of brain MS plaques. MATERIALS & METHODS: In this analytic cross sectional study, sample size was assessed as 40 people to detect any significant difference between two sequences with a level of 0...
2017: Iranian Journal of Child Neurology
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