![]() The bore to barrel length ratio is called caliber in naval gunnery, : 81 but is called length in army artillery. This is also sometimes indicated using the prefix L/ so for example, the most common gun for the Panzer V tank is described as a "75 mm L/70," meaning a barrel with an internal bore of 75 mm, and 5,250 mm long (17 ft 2.69 in). They are 16 inches in diameter and the barrel is 800 inches long (16 × 50 = 800). : 81 As an example, the main guns of the Iowa-class battleships can be referred to as 16"/50 caliber. The effective length of the barrel (from breech to muzzle) is divided by the barrel diameter to give a dimensionless quantity. The length of the barrel (especially for larger guns) is often quoted in calibers, used, for example, in US Naval Rifles 3 in (76 mm) or larger. Driving band diameter was groove to groove diameter plus 0.02 inches (0.51 mm). Projectile bourrelet diameter specification was 0.015 inches (0.38 mm) less than land to land diameter with a minus manufacturing tolerance so average clearance was about 0.012 inches (0.30 mm). United States Navy guns typically used rifling depth between one-half and one percent of caliber. Steel artillery projectiles may have a forward bourrelet section machined to a diameter slightly smaller than the original land to land dimension of the barrel and a copper driving band somewhat larger than the groove to groove diameter to effectively seal the bore as it becomes enlarged by erosion during prolonged firing. The depth of rifling grooves (and the consequent ambiguity) increases in larger calibers. Projectiles fired from rifled barrels must be of the full groove to groove diameter to be effectively rotated by the rifling, but the caliber has sometimes been specified as the land to land diameter before rifling grooves were cut. The distance across the bore from groove to groove is greater than the distance from land to land. A rifled bore consists of alternating grooves and lands. patients with diabetes, suspected hypertension and stroke).Rifled barrels introduce ambiguity to measurement of caliber. Nevertheless, with continual development of retinal imaging techniques and newer understanding of the clinical significance of these retinal changes, there remains scope for the development of retinal vascular caliber measurements as a biomarker for vascular disease risk assessment in targeted areas and patient subgroups (e.g. However, while retinal image analysis provided exciting possibilities to study the pathogenesis of these diseases, its direct applicability in a clinical setting as a 'test' to predict cardiovascular diseases is yet to be established, particularly within the context of being used as a population screening tool. atherosclerosis, inflammation and endothelial dysfunction) and clinical cardiovascular diseases (hypertension, diabetes mellitus, stroke, kidney and heart diseases). Over the last decade, large population-based studies have shown that retinal vascular calibers are associated with a wide range of subclinical (e.g. Advances in fundus photography and retinal image analysis techniques have enabled the objective and accurate assessment of quantitative retinal vascular caliber measurement. The retinal vasculature provides a unique window to assess vascular health noninvasively and directly in vivo.
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