نتایج جستجو برای: spherical vessel
تعداد نتایج: 132886 فیلتر نتایج به سال:
introduction: this paper addresses a method for automatic detection of blood vessels in color fundus images which utilizes two main tools: image partitioning and local radon transform. material and methods: the input images are firstly divided into overlapping windows and then the radon transform is applied to each. the maximum of the radon transform in each window corresponds to the probable a...
Introduction Several MR methods require a mathematical model of microvasculature to extract physiological parameters such as blood volume fraction (BVf), vessel size index (VSI) and blood oxygen saturation. In the case of BVf and VSI, MR estimates obtained in healthy and tumoral tissues – although well correlated with histology – seemed too large [1]. As tumoral development can strongly alter t...
congenital anomalies of coronary arteries, albeit rare, may be significant contributors to angina pectoris, hemodynamic abnormalities, and sudden cardiac death. a 47-year-old man referred to us with atypical chest pain. electrocardiography demonstrated no significant ischemic changes, but cardiac troponin i test was positive. the patient underwent coronary angiography, which revealed a single c...
large intercoronary communications in the absence of obstructive coronary artery disease constitute a very rare coronary artery anomaly in which there is a readily visible connection between the 2 coronary arteries with a unidirectional or bidirectional blood flow; consequently, this anomaly may be misinterpreted as a functioning collateral vessel, indicative of an unrecognized proximal coronar...
From the view of differential geometry, a straight line is a geometric curve with the curvature κ(s) = 0. A plane curve is a family of geometric curves with torsion τ(s) = 0. Helix is a geometric curve with non-vanishing constant curvature κ and non-vanishing constant torsion τ [4]. The helix may be called a circular helix or W -curve [9]. It is known that straight line (κ(s) = 0) and circle (κ...
We present new computations of “intrinsic” symmetry groups for knots and links of 8 or fewer crossings. The standard symmetry group for a link is the mapping class group MCG(S, L) or Sym(L) of the pair (S, L). Elements in this symmetry group can (and often do) fix the link and act nontrivially only on its complement. We ignore such elements and focus on the “intrinsic” symmetry group of a link,...
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