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- Cammoun, L., et al.
(författare)
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A Review of Tensors and Tensor Signal Processing
- 2009
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Ingår i: Tensors in Image Processing and Computer Vision. - London : Springer London. - 9781848822986 ; , s. 1-32
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Bokkapitel (refereegranskat)abstract
- Tensors have been broadly used in mathematics and physics, since they are a generalization of scalars or vectors and allow to represent more complex properties. In this chapter we present an overview of some tensor applications, especially those focused on the image processing field. From a mathematical point of view, a lot of work has been developed about tensor calculus, which obviously is more complex than scalar or vectorial calculus. Moreover, tensors can represent the metric of a vector space, which is very useful in the field of differential geometry. In physics, tensors have been used to describe several magnitudes, such as the strain or stress of materials. In solid mechanics, tensors are used to define the generalized Hooke’s law, where a fourth order tensor relates the strain and stress tensors. In fluid dynamics, the velocity gradient tensor provides information about the vorticity and the strain of the fluids. Also an electromagnetic tensor is defined, that simplifies the notation of the Maxwell equations. But tensors are not constrained to physics and mathematics. They have been used, for instance, in medical imaging, where we can highlight two applications: the diffusion tensor image, which represents how molecules diffuse inside the tissues and is broadly used for brain imaging; and the tensorial elastography, which computes the strain and vorticity tensor to analyze the tissues properties. Tensors have also been used in computer vision to provide information about the local structure or to define anisotropic image filters.
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- Sandberg Wollheim, Magnhild, et al.
(författare)
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Pregnancy outcomes during treatment with interferon beta-1a in patients with multiple sclerosis.
- 2005
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Ingår i: Neurology. - : Ovid Technologies (Wolters Kluwer Health). - 1526-632X .- 0028-3878. ; 65:6, s. 802-806
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Tidskriftsartikel (refereegranskat)abstract
- Background: Although patients with multiple sclerosis (MS) are advised to stop interferon (IFN) beta-1a therapy before becoming pregnant, some patients become pregnant while on treatment. Methods: We examined individual patient data from eight clinical trials with IFN beta-1a. Results: Of 3,361 women in the studies, 69 pregnancies were reported, of which 41 were patients receiving (or who had stopped receiving within 2 weeks prior to conception) IFN beta-1a (in utero exposure group), 22 were patients who discontinued IFN beta-1a treatment more than 2 weeks before conception (previous exposure group), and six were patients receiving placebo. The 41 in utero exposure pregnancies resulted in 20 healthy full-term infants, one healthy premature infant, nine induced abortions, eight spontaneous abortions, one fetal death, and one congenital anomaly (hydrocephalus). One patient was lost to follow-up. The 22 previous exposure pregnancies resulted in 20 full-term healthy infants, one healthy premature infant, and one birth-related congenital anomaly (Erb palsy) Conclusions: The majority (21/31) of pregnancies that had the potential to go to full term produced healthy infants. The rate of spontaneous abortion was higher, but not significantly so, in the in utero exposure group compared to general population estimates. Until more exposure data become available, patients remain advised to stop IFN beta therapy before becoming pregnant.
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