Diagnostic ultrasound probes: a typology and overview of technologies

AbstractThe routine clinical use of diagnostic ultrasound (US) has spread considerably worldwide in recent decades. This is due in large part to the availability of US probes that enable a wide range of clinical applications as well as provide performance benefits arising from technological improvements. This paper describes the current commercially available US probe types, lists some of their clinical applications and briefly explains the technologies that are responsible for recent enhancements in image quality and ergonomics. Our intention is to summarize information that will allow healthcare professionals to select the appropriate probe for the intended use and the desired performance-price ratio.</jats:p

Transmission of climate, sea-level, and tectonic singals across river systems

This thesis investigates the impact of climatic, tectonic, and sea-level changes (external forcing) on river systems (source-to-sink) and how these changes are recorded in the stratigraphic record. It describes a newly developed numerical tool (PaCMod) to simulate the complex fluvial system sediment flux response to external forcing on a geological time scale. Numerical modelling simulations, combined with field data indicated that the late Quaternary evolution of the Golo River system (France) was controlled by a complex interaction of sea-level and climatic forcing. Stratigraphic analysis in the Panther Tongue delta (Utah) showed how different parts of an ancient shoreline reacted differently to the same changes in external forcing, which consequently, have a different stratigraphic expression along depositional strike.Geoscience & EngineeringCivil Engineering and Geoscience

Active faulting and folding along Jumilla Fault Zone, northeastern Betics, Spain

The Jumilla Fault Zone (JFZ) is an ENE-WSW topographic lineament in the external part of the eastern Betic Cordillera. It represents an active fault. Three small basins are aligned along the JFZ, the La Celia-, Alqueria- and Jumilla basins. The tectonic geomorphology of the La Celia- and Alqueria basins consists of folds, a set of normal fault scarps, strike-slip lineaments, fault-springs, tectonically-modified drainage lines and elevated gypsum/anhydrite diapirs. Two of the scarps are normal faults generated by the extensional collapse of one of the folds. The other scarps are secondary normal faults generated by transtensional left-lateral motions along the JFZ. Normal fault scarps that developed on conglomerates are considerably steeper (~ 30°) than those affecting softer marly materials (< 10°) as a consequence of their different erodibilities. Two natural springs reveal the sealing nature of the normal faults, which has resulted in a segmented groundwater system. These springs are the sources of the two largest ramblas (gullies) in the area. The onset of fault activity is constrained by the late Tortonian-Messinian age of the sedimentary rocks in the basins. Interbedded lavaflows and lamproitic dykes in the lacustrine sediments have been dated at 7.6-7.2 Ma. However, the morphology of fault scarps and relief of the diapirs suggest a younger age of the deformation. Results from modelling of fault scarp evolution indicate Middle Pleistocene and younger ages of faulting and scarp formation. Furthermore, in at least one of the fault scarps, Quaternary alluvial-pediment deposits are involved in the deformation. The drainage pattern anomalies and moderate earthquake activity (Mb 4.2) in the JFZ also indicate slow ongoing tectonic activity. In addition, the ENE prolongation of the JFZ (outside the study area) shows geodetic displacement rates of approximately 2 mm/year. We thus conclude that the JFZ is still active, despite the general lack of post-Messinian deposits in the studied basins. The discrepancy between the age of the tectonic landforms and the late Neogene age of the basin infill can be explained by an endo- to exhorheic change in the drainage system, due to the capture of the ancient basin lake system by tributaries of the nearby Segura river. The cessation of sedimentation in the basins resulted in the preservation of tectonic landforms. © 2013 Elsevier B.V. All rights reserved

Active faulting and folding along the Jumilla Fault Zone, northeastern Betics, Spain

The Jumilla Fault Zone (JFZ) is an ENE-WSW topographic lineament in the external part of the eastern Betic Cordillera. It represents an active fault. Three small basins are aligned along the JFZ, the La Celia-, Alqueria- and Jumilla basins. The tectonic geomorphology of the La Celia- and Alqueria basins consists of folds, a set of normal fault scarps, strike-slip lineaments, fault-springs, tectonically-modified drainage lines and elevated gypsum/anhydrite diapirs. Two of the scarps are normal faults generated by the extensional collapse of one of the folds. The other scarps are secondary normal faults generated by transtensional left-lateral motions along the JFZ. Normal fault scarps that developed on conglomerates are considerably steeper (~ 30°) than those affecting softer marly materials (<10°) as a consequence of their different erodibilities. Two natural springs reveal the sealing nature of the normal faults, which has resulted in a segmented groundwater system. These springs are the sources of the two largest ramblas (gullies) in the area. The onset of fault activity is constrained by the late Tortonian-Messinian age of the sedimentary rocks in the basins. Interbedded lavaflows and lamproitic dykes in the lacustrine sediments have been dated at 7.6-7.2 Ma. However, the morphology of fault scarps and relief of the diapirs suggest a younger age of the deformation. Results from modelling of fault scarp evolution indicate Middle Pleistocene and younger ages of faulting and scarp formation. Furthermore, in at least one of the fault scarps, Quaternary alluvial-pediment deposits are involved in the deformation. The drainage pattern anomalies and moderate earthquake activity (Mb 4.2) in the JFZ also indicate slow ongoing tectonic activity. In addition, the ENE prolongation of the JFZ (outside the study area) shows geodetic displacement rates of approximately 2 mm/year. We thus conclude that the JFZ is still active, despite the general lack of post-Messinian deposits in the studied basins. The discrepancy between the age of the tectonic landforms and the late Neogene age of the basin infill can be explained by an endo- to exhorheic change in the drainage system, due to the capture of the ancient basin lake system by tributaries of the nearby Segura river. The cessation of sedimentation in the basins resulted in the preservation of tectonic landforms

Impact of external forcing and catchment response on sediment flux

Geoscience & EngineeringCivil Engineering and Geoscience

Non-linear response of the Golo River system, Corsica, France, to Late Quaternary climatic and sea level variations

Disentangling the impact of climatic and sea level variations on fluvio-deltaic stratigraphy is still an outstanding question in sedimentary geology and geomorphology. We used the Golo River system, Corsica, France, as a natural laboratory to investigate the impact of Late Quaternary climate and sea level oscillations on sediment flux from a catchment and on fluvio-deltaic stratigraphy. We applied a numerical model, PaCMod, which calculates catchment sediment production and transport and compared modeling output to the sedimentary record of the Golo alluvial-coastal plain, whose chronology was reinterpreted using new optical stimulated luminescence (OSL) ages on feldspars. Our modeling, OSL ages, and geomorphological results indicate that the two main phases of braidplain development in the Golo alluvial-coastal plain occurred during the cold–dry phases of MIS5 and during the late MIS4-early MIS3, as a consequence of high catchment erosion rates and low water discharge. Incision and sediment reworking occurred during sea level low stand periods (MIS4 and late MIS3-MIS2). High sediment flux pulses from the catchment outlet were generated during the Lateglacial and early Holocene, as a result of the release of sediments previously stored within the catchment and enhanced snowmelt. Our results suggest a non-linear response of the Golo River system to climatic and eustatic changes, caused by sediment storage within the catchment and geomorphological thresholds. This indicates that a direct comparison between palaeo-climate and stratigraphy is not possible without considering catchment sediment storage and sediment transport delays out of the catchment

Transcranial Ultrasound and Magnetic Resonance Image Fusion With Virtual Navigator

The Virtual Navigator (VN) technology was used for the fusion of transcranial Ultrasound (US) and brain Magnetic Resonance Images (MRI), with a repeatability error under 0.1 cm. The superimposition of US to the previously acquired MRI volume consisted of external point-based registration, that was subsequently refined with image-based registration of internal brain structures. The common registration procedure with the usage of external fiducial markers acquired with the two modalities was improved using facial anatomical landmarks, with a reduction of the internal targeted structure residual shift (maximum 0.7 cm in the cranio-caudal direction). This allowed the investigation of Deep Cerebral Veins and dural sinuses insonated from the condyloid process of the mandible, a recently introduced US window. The fusion of these vessels to the MRI volume provided their anatomical position and helped excluding false Doppler signal sources

Upstream versus downstream forcing: The response of the Golo River system, Corsica, to late quaternary climatic and eustatic oscillations

Geoscience & EngineeringCivil Engineering and Geoscience