IsotropyIn physics and geometry, isotropy () is uniformity in all orientations. Precise definitions depend on the subject area. Exceptions, or inequalities, are frequently indicated by the prefix a- or an-, hence anisotropy. Anisotropy is also used to describe situations where properties vary systematically, dependent on direction. Isotropic radiation has the same intensity regardless of the direction of measurement, and an isotropic field exerts the same action regardless of how the test particle is oriented.
Cerebral venous sinus thrombosisCerebral venous sinus thrombosis (CVST), cerebral venous and sinus thrombosis or cerebral venous thrombosis (CVT), is the presence of a blood clot in the dural venous sinuses (which drain blood from the brain), the cerebral veins, or both. Symptoms may include severe headache, visual symptoms, any of the symptoms of stroke such as weakness of the face and limbs on one side of the body, and seizures, which occur in around 40% of patients.
Ultrasonography of chronic venous insufficiency of the legsUltrasonography of suspected or previously confirmed chronic venous insufficiency of leg veins is a risk-free, non-invasive procedure. It gives information about the anatomy, physiology and pathology of mainly superficial veins. As with heart ultrasound (echocardiography) studies, venous ultrasonography requires an understanding of hemodynamics in order to give useful examination reports. In chronic venous insufficiency, sonographic examination is of most benefit; in confirming varicose disease, making an assessment of the hemodynamics, and charting the progression of the disease and its response to treatment.
Purkinje fibersThe Purkinje fibers (pɜːrˈkɪndʒi ; ˈpurkɪɲɛ; Purkinje tissue or subendocardial branches) are located in the inner ventricular walls of the heart, just beneath the endocardium in a space called the subendocardium. The Purkinje fibers are specialized conducting fibers composed of electrically excitable cells. They are larger than cardiomyocytes with fewer myofibrils and many mitochondria. They conduct cardiac action potentials more quickly and efficiently than any of the other cells in the heart's electrical conduction system.
Vascular anomalyA vascular anomaly is any of a range of lesions from a simple birthmark to a large tumor that may be disfiguring. They are caused by a disorder of the vascular system. A vascular anomaly is a localized defect in blood or lymph vessels. These defects are characterized by an increased number of vessels, and vessels that are both enlarged and sinuous. Some vascular anomalies are congenital, others appear within weeks to years after birth, and others are acquired by trauma or during pregnancy.
PhotorealismPhotorealism is a genre of art that encompasses painting, drawing and other graphic media, in which an artist studies a photograph and then attempts to reproduce the image as realistically as possible in another medium. Although the term can be used broadly to describe artworks in many different media, it is also used to refer specifically to a group of paintings and painters of the American art movement that began in the late 1960s and early 1970s.
ParchmentParchment is a writing material made from specially prepared untanned skins of animals—primarily sheep, calves, and goats. It has been used as a writing medium for over two millennia. Vellum is a finer quality parchment made from the skins of young animals such as lambs and young calves. It may be called animal membrane by libraries and museums that wish to avoid distinguishing between parchment and the more-restricted term vellum (see below).
