SCHMIDT-NIELSEN, BODIL, AND ROBERTA O’DELL. Structure and concentrating mechanism in the mammalian kidney. Am. J. Physiol. 200 (6) : I I I g-I I 24. 1961 .-In a number of mammalian kidneys a close correlation was found between renal medullary thickness and ability to concentrate electrolytes in the urine, indicating that both outer and inner zone of the medulla act as a countercurrent multiplie...

In vertebrate peripheral nerves, the insulating myelin sheath is formed by Schwann cells, which generate flattened membrane processes that spiral around axons and form compact myelin by extrusion of cytoplasm and adhesion of apposed intracellular and extracellular membrane surfaces. Cytoplasm remains within the innermost and outermost tongues, in the paranodal loops bordering nodes of Ranvier a...

[1] The observed differences between complex craters and multi-ringed basins are described and a combined ‘‘transient cavity/displaced zone/melt cavity’’ model is explored to account for the observations. In this ‘‘nested melt-cavity model’’, the increasing influence of the percentage of the target undergoing impact melting at the sub-impact point with increasing size (the differential melt sca...

The Neuro Image Quiz, Answers T.P. Thomas P. Naidich Thomas P. Naidich, MD, Division of Neuroimaging, Children’s Memorial Hospital, 2300 Children’s Plaza, Chicago, IL 60614 (USA) These images demonstrate a well-circumscribed lobu-lated erosion of the anterior parietal bone, situated just posterior to the coronal suture. In this case the zone of transition from obviously normal bone to obviously...

Two of the largest geomagnetic storms of the last decade were witnessed in 2015. On 17 March 2015, a coronal mass ejection-driven event occurred with a Dst (storm time ring current index) value reaching -223 nT. On 22 June 2015 another strong storm (Dst reaching -204 nT) was recorded. These two storms each produced almost total loss of radiation belt high-energy (E ≳ 1 MeV) electron fluxes. Fol...