Vertical structure of recent arctic warming from observed data and reanalysis products

Spatiotemporal patterns of recent (1979–2008) air temperature trends are evaluated using three reanalysis datasets and radiosonde data. Our analysis demonstrates large discrepancies between the reanalysis datasets, possibly due to differences in the data assimilation procedures as well as sparseness and inhomogeneity of high-latitude observations. We test the robustness of Arctic tropospheric warming based on the ERA-40 dataset. ERA-40 Arctic atmosphere temperatures tend to be closer to the observed ones in terms of root mean square error compare to other reanalysis products used in the article. However, changes in the ERA-40 data assimilation procedure produce unphysical jumps in atmospheric temperatures, which may be the likely reason for the elevated tropospheric warming trend in 1979-2002. NCEP/NCAR Reanalysis show that the near-surface upward temperature trend over the same period is greater than the tropospheric trend, which is consistent with direct radiosonde observations and inconsistent with ERA-40 results. A change of sign in the winter temperature trend from negative to positive in the late 1980s is documented in the upper troposphere/lower stratosphere with a maximum over the Canadian Arctic, based on radiosonde data. This change from cooling to warming tendency is associated with weakening of the stratospheric polar vortex and shift of its center toward the Siberian coast and possibly can be explained by the changes in the dynamics of the Arctic Oscillation. This temporal pattern is consistent with multi-decadal variations of key Arctic climate parameters like, for example, surface air temperature and oceanic freshwater content. Elucidating the mechanisms behind these changes will be critical to understanding the complex nature of high-latitude variability and its impact on global climate change

Nikolay Ivanovich Pirogov (1810–1881): Anatomical research to develop surgery

The 19th century Russian surgeon Nikolay Ivanovich Pirogov believed passionately in the importance of anatomy for surgeons. His interest in anatomy began as a medical student in Moscow. After graduating in 1828 Pirogov entered the postgraduate German-Baltic University of Dorpat (now Tartu in the Republic of Estonia) where he studied anatomy and surgery. After completing his study, he remained to research the consequences of ligation of the aorta in a series of animal experiments, which formed the core of his doctoral thesis. He wanted to determine the feasibility of aortic ligation as a treatment for patients with an aneurysm of the aorta or iliac artery. He discovered that success was only likely when the aorta was ligated between the two mesenteric arteries and the ligature gradually tightened, an approach surgically difficult in humans. Pirogov then spent 2 years at the Charité Hospital in Berlin before returning to Russia. In 1841, he was appointed Professor of Applied Anatomy and Surgery at the Imperial Medico-Surgical Academy in Saint Petersburg. He instituted the teaching of microscopy and histology to the medical curriculum and in 1846 formed the Institute for Applied Anatomy within the academy, where in addition to teaching medical students future teachers of anatomy in Russia were trained. Pirogov published extensively on anatomy, including several anatomical atlases, the most notable his three-dimensional atlas of topographical anatomy published in four volumes between 1852 and 1859. Today Pirogov’s contributions to anatomy are remembered in a number of anatomical structures named after him. Stem cells & developmental biolog