All periglacial and glacial landforms investigated in the Northern Foothills have a very thin active layer (0.1–0.3 m thickness) overlying a thin permafrost layer, characterised by electrical resistivities ranging between 13 and 50 kΩm and by different thicknesses. Below this surficial layer, different types of ground ice (with a resistivity range from 8000 to 0.1 kΩm) were detected. These different types of ground ice permitted ice‐cored rock glaciers to be distinguished from ice‐cemented rock glaciers, subsea permafrost to be identified in some raised beaches, and other interpretations to be suggested about a debris‐covered glacier. These results have been obtained by vertical electrical soundings (VES) carried out in ice‐free areas of the Northern Foothills, near Terra Nova Bay Station during the tenth national Italian expedition in Antarctica (1994–1995). In these areas on the basis of previous geomorphological research, some landforms such as rock glaciers, raised beaches with patterned ground and debris‐covered glaciers were chosen to carry out the VES. The electrical prospection can be considered a good means for understanding the origins of landforms in ice‐free areas of Antarctica and for making a contribution to the palaeoenvironmental reconstruction of this continent.
Geomorphological and glaciological features are represented on a georeferenced satellite image mosaic of the Mount Murchison quadrangle, northern Victoria Land, Antarctica (73-748 S, 162-166830 0 E), at a scale of 1 : 250 000. Landforms and deposits of glacial and periglacial environments, forms related to mass wasting, wind action, weathering and geological structures are identified and mapped. The chronological sequence of landforms and deposits, morphography and lithology is also indicated. Glacier velocities (up to 180 m a -1 ) and ice-front fluctuations (1964-99) were determined by analysis of aerial photography and satellite imagery. Airborne radar surveys reveal that the greatest ice thickness (about 1500 m) is located in the grounding zone of Aviator Glacier. Up to 1000 m of ice bury the subglacial relief of Deception Plateau, Hercules Névé and the Deep Freeze Range. Snow accumulation rates (average = 170 kg m -2 a -1 ) exhibit an overall negative correlation with altitude and distance from the coast. The relationships among relict erosional landforms and volcanic activity provide chronological constraints for the palaeogeographic evolution of this sector of the Transantarctic Mountains.
The utility of animal models in preclinical research has been increasing by the availability of methods for in vivo imaging. In particular, techniques like single photon emission computed tomography (SPECT) show high potential, which is usually limited by spatial resolution. This represents an important parameter influencing scanner design, given the small size of the anatomical structures to be investigated. The purpose of the present work was to assess the performance of a scintigraphic system with improved spatial resolution based on our previous detector by applying the Super Spatial Resolution (SSR). Our dual-head SPECT system is composed of gamma cameras based on the Hamamatsu H13700 position-sensitive photomultiplier tube (PSPMT). In each detector head, the PSPMT is coupled to a 28×28 array of CRY018 scintillation crystals. The pure Tungsten parallel square hole collimator ensures the position sensitivity, and a dedicated resistive chain readout so as an ADC board have been proprietary designed. To finalize the mechanical development of the SSR-SPECT system several tests were carried out. Based on the results obtained in the test phase, a partial review of the mechanical design was performed. Then a dedicated machine handling software was developed, and in particular, a kinematic software debugging and testing was assessed. Finally, several experiments were carried out by using Derenzo phantoms and capillaries filled with radioactive sources. Finally, the performance of our system was evaluated performing small animal imaging studies. The SPECT spatial resolution was experimentally determined to be about 1.6 mm. We reach a resolution of 1.18 mm by applying the SSR based on two images. The results of this study demonstrated the good capability of the system as a suitable tool for preclinical imaging especially in fields like neuroscience for the study of small brain structures.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.