Search results for "microscopic"
showing 10 items of 177 documents
Phase Behavior and Microscopic Transport Processes in Binary Metallic Alloys: Computer Simulation Studies
2009
In a binary liquid mixture, different kinds of phase transitions can occur that are associated with various mass transport phenomena in the liquid. First, there is the possibility that the liquid undergoes a liquid-liquid demixing transition [1]. Near the critical point of this transition, a slowing down of dynamic properties is observed which is characterized, e.g., by a vanishing interdiffusion coefficient at the critical point [2, 3]. Another possible phase transition is a first-order transition of the liquid into a crystalline structure. In this case, crystal nucleation and growth are limited by the diffusive transport in the liquid [1, 4]. In a binary liquid, crystal nucleation process…
Microscopic biasing of discrete-time quantum trajectories
2021
We develop a microscopic theory for biasing the quantum trajectories of an open quantum system, which renders rare trajectories typical. To this end we consider a discrete-time quantum dynamics, where the open system collides sequentially with qubit probes which are then measured. A theoretical framework is built in terms of thermodynamic functionals in order to characterize its quantum trajectories (each embodied by a sequence of measurement outcomes). We show that the desired biasing is achieved by suitably modifying the Kraus operators describing the discrete open dynamics. From a microscopical viewpoint and for short collision times, this corresponds to adding extra collisions which enf…
Grades of atypia in tubular and villous adenomas of the human colon. An electron microscopic study.
1980
Of a total of 544 tubular, villous and tubulo-villous adenomas of the human colon which were investigated by light microscopy, six tubular and six villous adenomas were examined under the electron microscope. It was shown that the two types of adenoma differ in their tissue architecture, but not in their cytological appearance. Different grades of epithelial atypia occur in both types of adenoma. These are designated as grades I to III, correspond to mild, moderate and severe atypia respectively. Whereas adenoma cells with atypia grade I clearly show a cytological relationship with crypt epithelia of the normal colonic mucosa under the electron microscope, adenoma cells with atypia grade II…
Angiogenesis in oral lichen planus: an in vivo and immunohistological evaluation.
2010
Oral lichen planus (OLP) is an autoimmune disease with an inflammatory pathogenesis. The angiogenetic phenomenon is a mechanism at the base of the pathogenesis of chronic inflammatory processes. The aim of this research is to evaluate the angiogenetic phenomenon, comparing an in vitro method with an in vivo one. Thirty OLP patients and 30 healthy subjects were enrolled in the study. Immunohistochemical analysis of the vascular-endothelial growth factor (VEGF) and vascular-endothelial adhesion molecules were carried out by the means of primary antibodies and anti-CD34, anti-VEGF, anti-CD106 antigen (VCAM-1) and anti-CD54 antigen (ICAM-1). Capillary density and others capillaroscopic paramete…
Evaluating the microscopic effect of brushing stone tools as a cleaning procedure
2020
Cleaning stone tool surfaces is a common procedure in lithic studies. The first step widely applied at any archeological site (and/or at field laboratories) is the gross removal of sediment from the surfaces of artifacts. Lithic surface alterations due to mechanical action applied in wet or dry cleaning regimes have never been examined at a microscopic scale. This could have important implications in traceology, as any modern surface modifications inflicted on archeological artifacts might compromise their functional interpretations. The current trend toward quantification of use-wear traces makes the testing even more important, as even slight, apparently invisible surface alterations migh…
Surgical treatment of primary gastrointestinal stromal tumors (GISTs): Management and prognostic role of R1 resections
2020
Abstract Background Surgery represents the best treatment for primary gastrointestinal stromal tumors (GISTs). The aim of this study is to analyse outcomes of surgical management in order to evaluate the influence of microscopically R1 margins on survival and recurrence in patients affected by GISTs. Methods The study reviewed retrospective data from 74 patients surgically treated for primary GISTs without metastasis at diagnosis. Clinical and pathological findings, surgical procedures, information about follow up and outcomes were analyzed. Results Recurrence rate was low and no patients died in the R1 group during the follow up period. The difference in recurrence free survival for patien…
Mesoscopic organization in ionic liquids.
2017
We discuss some published results and provide new observations concerning the high level of structural complexity that lies behind the nanoscale correlations in ionic liquids (ILs) and their mixtures with molecular liquids. It turns out that this organization is a consequence of the hierarchical construction on both spatial (from ångström to several nanometer) and temporal (from fraction of picosecond to hundreds of nanosecond) scales, which requires joint use of experimental and computational tools. © 2017, Springer International Publishing Switzerland.
Discrete-lattice theory for Frenkel-defect aggregation in irradiated ionic solids
1998
Institut fu ¨r Physikalische und Theoretische Chemie, Technische Universitat Braunschweig, D-38106 Braunschweig, Germany~Received 11 September 1997; revised manuscript received 6 April 1998!A microscopic theory of diffusion-controlled aggregation of radiation Frenkel defects—called in ionic solidsH and F centers—is presented. This is based on a discrete-lattice formalism for the single defect densities~concentrations! and the coupled joint densities of similar and dissimilar defects treated in terms of a modifiedKirkwood superposition approximation. The kinetics of defect aggregation is studied in detail; the cooperativecharacter of this process for both types of complementary defects is sho…
Electron microscopic study on the larval and adult corpus allatum of Oncopeltus fasciatus dallas (insecta, heteroptera)
1973
1. The ultrastructure of the corpora allata of last larval instars and adults of Oncopeltus was studied. The unpaired gland undergoes submicroscopic alterations and shows signs of degradation in old animals. The organ is partly covered and penetrated by corpus cardiacum tissue. Axons with different types of neurosecretory granules form synaptoid contacts with the corpus allatum cells.