نتایج جستجو برای: penumbra
تعداد نتایج: 1751 فیلتر نتایج به سال:
High-resolution observations of horizontal motions in the penumbra are needed to complement concept penumbrae obtained from spectropolarimetry. Time series intensity images a large sunspot AR 10634 acquired with Swedish Solar Telescope G band and red continuum analysed. The two simultaneous time last six hours five minutes. Horizontal penumbral grains (PGs), structures dark bodies filaments, ou...
Abstract In addition to the Evershed flow directed from umbra toward outer boundary of a sunspot, under special circumstances counter (CEF) in opposite direction also occurs. We aim characterize proper motions and evolution three CEFs observed by Solar Optical Telescope on board Japanese Hinode spacecraft Helioseismic Magnetic Imager Dynamics Observatory. use state-of-the-art inversions radiati...
BACKGROUND AND PURPOSE We sought to assess whether the volume of the ischemic penumbra can be estimated more accurately by altering the threshold selected for defining perfusion-weighting imaging (PWI) lesions. METHODS DEFUSE is a multicenter study in which consecutive acute stroke patients were treated with intravenous tissue-type plasminogen activator 3 to 6 hours after stroke onset. Magnet...
BACKGROUND AND PURPOSE To determine whether perfusion computed tomography (PCT) adds value to noncontrast head CT (NCT), CT angiogram (CTA), and clinical assessment in patients suspected of acute ischemic stroke. METHODS We retrospectively reviewed 165 patients with acute ischemic stroke. PCT was used to calculate the volumes of infarct core and ischemic penumbra on admission. Other imaging d...
BACKGROUND AND PURPOSE Various CTP parameters have been used to identify ischemic penumbra. The purpose of this study was to determine the optimal CTP parameter and threshold to distinguish true "at-risk" penumbra from benign oligemia in acute stroke patients without reperfusion. MATERIALS AND METHODS Consecutive stroke patients were screened and 23 met the following criteria: 1) admission sc...
Background: Perfusion computed tomography (CT) is an evolving technique in the diagnosis of acute stroke. After complex deconvolution algorithms, perfusion color maps-cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT)— are produced, they give visual confirmation of perfusion deficit in ischemic area, but some discrepancies exist regarding this technique in relia...
BACKGROUND AND PURPOSE We investigated whether computed tomography (CT) perfusion-derived cerebral blood flow (CBF) and cerebral blood volume (CBV) could be used to differentiate between penumbra and infarcted gray matter in a limited, exploratory sample of acute stroke patients. METHODS Thirty patients underwent a noncontrast CT (NCCT), CT angiography (CTA), and CT perfusion (CTP) scan withi...
In order to study umbral oscillations, running penumbral waves and the relationship between them, we analyzed CCD, high resolution, sunspot observations obtained at center and the wings of the Hα line and the Fe I 5576 Å line. The UBF filter was used in order to produce high cadence sequences of filtergrams. Images were processed to remove the sharp intensity gradient between the umbra and the ...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید