نتایج جستجو برای: physical penumbra

تعداد نتایج: 666538  

2018
Graeme A Deuchar David Brennan William M Holmes Martin Shaw I Mhairi Macrae Celestine Santosh

The ability to identify metabolically active and potentially salvageable ischaemic penumbra is crucial for improving treatment decisions in acute stroke patients. Our solution involves two complementary novel MRI techniques (Glasgow Oxygen Level Dependant (GOLD) Metabolic Imaging), which when combined with a perfluorocarbon (PFC) based oxygen carrier and hyperoxia can identify penumbra due to d...

2013
Emmanuel Carrera P. Simon Jones Rhiannon S. Morris Josef Alawneh Young T. Hong Franklin I. Aigbirhio Tim D. Fryer T. Adrian Carpenter Elizabeth A. Warburton Jean-Claude Baron

After stroke, penumbral salvage determines clinical recovery. However, the rescued penumbra may be affected by selective neuronal loss, as documented both histopathologically in animals and using the validated in vivo positron emission tomography marker C-flumazenil in humans. However, whether the non-infarcted penumbra is capable of neuronal activation, and how selective neuronal loss may inte...

Journal: :Revista colombiana de antropologia 2022

Desde la segunda mitad del siglo XX, los proyectos de modernización en el occidente México intensificaron modificación paisaje con infraestructura para reproducción especies. En este fotoensayo rastreo movilidad una ellas, peces. Específicamente exploro figura pez ciego como narrativa modernidad que provee imagen penumbra. Si es un proyecto situado brinda luces, sugiero penumbra peces zona inte...

Journal: :Brain : a journal of neurology 2013
Emmanuel Carrera P Simon Jones Rhiannon S Morris Josef Alawneh Young T Hong Franklin I Aigbirhio Tim D Fryer T Adrian Carpenter Elizabeth A Warburton Jean-Claude Baron

After stroke, penumbral salvage determines clinical recovery. However, the rescued penumbra may be affected by selective neuronal loss, as documented both histopathologically in animals and using the validated in vivo positron emission tomography marker (11)C-flumazenil in humans. However, whether the non-infarcted penumbra is capable of neuronal activation, and how selective neuronal loss may ...

Journal: :Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism 2015
Friedrich Wetterling Lindsay Gallagher Jim Mullin William M Holmes Chris McCabe I Mhairi Macrae Andrew J Fagan

Tissue sodium concentration increases in irreversibly damaged (core) tissue following ischemic stroke and can potentially help to differentiate the core from the adjacent hypoperfused but viable penumbra. To test this, multinuclear hydrogen-1/sodium-23 magnetic resonance imaging (MRI) was used to measure the changing sodium signal and hydrogen-apparent diffusion coefficient (ADC) in the ischemi...

2016
Audrey Kueh Jason M. Warnett Gregory J. Gibbons Julia Brettschneider Thomas E. Nichols Mark A. Williams Wilfrid S. Kendall

BACKGROUND In computed tomography (CT), the spot geometry is one of the main sources of error in CT images. Since X-rays do not arise from a point source, artefacts are produced. In particular there is a penumbra effect, leading to poorly defined edges within a reconstructed volume. Penumbra models can be simulated given a fixed spot geometry and the known experimental setup. OBJECTIVE This p...

2009
J. H. Thomas

Recent progress in theoretical modeling of a sunspot is reviewed. The observed properties of umbral dots are well reproduced by realistic simulations of magnetoconvection in a vertical, monolithic magnetic field. To understand the penumbra, it is useful to distinguish between the inner penumbra, dominated by bright filaments containing slender dark cores, and the outer penumbra, made up of dark...

2013
Radzina Maija Krumina Gaida Kupcs Karlis Miglane Evija

BACKGROUND Perfusion computed tomography (CT) is a relatively new technique that allows fast evaluation of cerebral hemodynamics by providing perfusion maps and gives confirmation of perfusion deficits in ischemic areas. Some controversies exist regarding accuracy of quantitative detection of tissue viability: penumbra (tissue at risk) or core (necrosis). PURPOSE To define brain tissue viabil...

2010
Sungjin Park Yongwook Jung

Instrumental role of Na(+) and Ca(2+) influx via Na(+)/K(+) adenosine triphosphatase (Na(+)/K(+)-ATPase) and Na(+)/Ca(2+) exchanger 1 (NCX1) is examined in the N-Methyl-D-aspartate (NMDA) receptor-mediated pathogenesis of penumbra after focal cerebral ischemia. An experimental model of 3, 6, and 24 h focal cerebral ischemia by permanent occlusion of middle cerebral artery was developed in rats....

Journal: :Computational and mathematical methods in medicine 2016
Dong Zhou Hui Zhang Peiqing Ye

Lateral penumbra of multileaf collimator plays an important role in radiotherapy treatment planning. Growing evidence has revealed that, for a single-focused multileaf collimator, lateral penumbra width is leaf position dependent and largely attributed to the leaf end shape. In our study, an analytical method for leaf end induced lateral penumbra modelling is formulated using Tangent Secant The...

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