Karel Frederik Wenckebach "second degree AV block" and later named the "Wenckebach phenomenon" and reclassified as Mobitz type I block in Mobitz's 1924 paper. A similar phenomenon can also occur in the Sinoatrial node where it gives rise to Type I second degree SA block, and this is also known as a Wenckebach block; the two have distinct features on an ECG however. Wenckebach is credited for describing the median bundle of the heart's conductive system that connects the sinoatrial node to the atrioventricular node. This bundle was named Wenckebach's bundle, and is also known as the middle internodal tract. Wenckebach's bundle is
Lunar node a location by averaging the height of the lowest tide recorded at that location each day during a 19-year recording period, known as the National Tidal Datum Epoch. The 19-year recording period is the nearest full-year count to the 18.6-year cycle of the lunar nodes. Lunar node A lunar node is either of the two orbital nodes of the Moon, that is, the two points at which the orbit of the Moon intersects the ecliptic. The "ascending" (or "north") node is where the Moon moves into the northern ecliptic hemisphere, while the "descending" (or "south") node is where the Moon