The turbulent dynamics of Jupiter's and Saturn's weather layers: order out of chaos?
GEOSCIENCE LETTERS
Authors: Read, Peter L.; Young, Roland M. B.; Kennedy, Daniel
Abstract
The weather layers of the gas giant planets, Jupiter and Saturn, comprise the shallow atmospheric layers that are influenced energetically by a combination of incoming solar radiation and localised latent heating of condensates, as well as by upwelling heat from their planetary interiors. They are also the most accessible regions of those planets to direct observations. Recent analyses in Oxford of cloud-tracked winds on Jupiter have demonstrated that kinetic energy is injected into the weather layer at scales comparable to the Rossby radius of deformation and cascades both upscale, mostly into the extra-tropical zonal jets, and downscale to the smallest resolvable scales in Cassini images. The large-scale flow on both Jupiter and Saturn appears to equilibrate towards a state which is close to marginal instability according to Arnol'd's 2nd stability theorem. This scenario is largely reproduced in a hierarchy of numerical models of giant planet weather layers, including relatively realistic models which seek to predict thermal and dynamical structures using a full set of parameterisations of radiative transfer, interior heat sources and even moist convection. Such models include (amongst others) the Jason GCM, developed in Oxford, which also represents the formation of (energetically passive) clouds of NH3, NH4SH and H2O condensates and the transport of condensable tracers. Recent results show some promise in comparison with observations from the Cassini and Juno missions, but some observed features (such as Jupiter's Great Red Spot and other compact ovals) are not yet captured spontaneously by most weather layer models. We review recent work in this vein and discuss a number of open questions for future study.
The cytologic and immunohistochemical findings of pancreatic mixed acinar-endocrine carcinoma
DIAGNOSTIC CYTOPATHOLOGY
Authors: Whitehair, Rachel; Stelow, Edward B.
Abstract
Background The classification of epithelioid pancreatic neoplasms based on fine-needle aspiration (FNA) is important for proper management, as distinction of pancreatic neuroendocrine neoplasms from other similar appearing lesions can result in significantly different treatment. Mixed acinar-endocrine carcinomas (MAEC) are genetically related to acinar carcinomas and are treated as such. We reviewed cases of MAEC to better characterize their cytologic and immunohistochemical features. Methods Eight FNAs of MAECs were identified and reviewed. A chart review for each case was conducted. Results All patients were male, 42-68 years of age, and presented with either Stage 3 or 4 disease. Smear backgrounds of all cases showed naked nuclei without significant necrosis. The smears were cellular with cells arranged in either three-dimensional (3D) clusters with intervening capillaries or singly dispersed. Acinar formation was a prominent feature. Cells were round to oval with small to moderate amounts of delicate cytoplasm. The nuclei were round to oval with mild to moderate anisonucleosis with granular chromatin and small nucleoli. Apoptotic bodies and mitoses were noted in most cases, with Ki67 indices of 10%-48%. All tumors, by definition, demonstrated expression of trypsin and synaptophysin with variable chromogranin expression (50%). Conclusion The cytology of acinar cell carcinoma shares features with aspirates of other nonductal adenocarcinoma neoplasms of the pancreas. A clue to the diagnosis is that tumors show high Ki67 indices and a diagnosis of MAEC should be excluded anytime a diagnosis of Grade 2 or 3 well-differentiated neuroendocrine tumor or high-grade neuroendocrine carcinoma is in the differential.