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  2. Kidney stone disease - Wikipedia

    en.wikipedia.org/wiki/Kidney_stone_disease

    Renal calculi typically form in the kidney and leave the body in the urine stream. [2] A small calculus may pass without causing symptoms. [2] If a stone grows to more than 5 millimeters (0.2 inches), it can cause blockage of the ureter, resulting in sharp and severe pain in the lower back that often radiates downward to the groin (renal colic).

  3. Hydronephrosis - Wikipedia

    en.wikipedia.org/wiki/Hydronephrosis

    This means an anteroposterior diameter of less than 4 mm in fetuses up to 32 weeks of gestational age and 7 mm afterwards. [18] In adults, cutoff values for renal pelvic dilation have been defined differently by different sources, with anteroposterior diameters ranging between 10 and 20 mm. [ 19 ] About 13% of normal healthy adults have a ...

  4. Nephrocalcinosis - Wikipedia

    en.wikipedia.org/wiki/Nephrocalcinosis

    Kidney showing circumscribed calcium deposits together with a partial stag horn calculus. Nephrocalcinosis , once known as Albright's calcinosis after Fuller Albright , is a term originally used to describe the deposition of poorly soluble calcium salts in the renal parenchyma due to hyperparathyroidism .

  5. Shoelace formula - Wikipedia

    en.wikipedia.org/wiki/Shoelace_formula

    Shoelace scheme for determining the area of a polygon with point coordinates (,),..., (,). The shoelace formula, also known as Gauss's area formula and the surveyor's formula, [1] is a mathematical algorithm to determine the area of a simple polygon whose vertices are described by their Cartesian coordinates in the plane. [2]

  6. Napkin ring problem - Wikipedia

    en.wikipedia.org/wiki/Napkin_ring_problem

    In this case the volume of the band is the volume of the whole sphere, which matches the formula given above. An early study of this problem was written by 17th-century Japanese mathematician Seki Kōwa. According to Smith & Mikami (1914), Seki called this solid an arc-ring, or in Japanese kokan or kokwan. [1]

  7. List of formulae involving π - Wikipedia

    en.wikipedia.org/wiki/List_of_formulae_involving_π

    where C is the circumference of a circle, d is the diameter, and r is the radius.More generally, = where L and w are, respectively, the perimeter and the width of any curve of constant width.

  8. Radius of curvature - Wikipedia

    en.wikipedia.org/wiki/Radius_of_curvature

    Let γ be as above, and fix t.We want to find the radius ρ of a parametrized circle which matches γ in its zeroth, first, and second derivatives at t.Clearly the radius will not depend on the position γ(t), only on the velocity γ′(t) and acceleration γ″(t).

  9. Wirtinger derivatives - Wikipedia

    en.wikipedia.org/wiki/Wirtinger_derivatives

    In complex analysis of one and several complex variables, Wirtinger derivatives (sometimes also called Wirtinger operators [1]), named after Wilhelm Wirtinger who introduced them in 1927 in the course of his studies on the theory of functions of several complex variables, are partial differential operators of the first order which behave in a very similar manner to the ordinary derivatives ...