OBJECTIVE Radiographically, a central venous catheter (CVC) tip should lie at the level of the right tracheobronchial angle. Precalculation of length of CVC insertion may avoid unnecessary catheter malposition. The purpose of this study was to assess the accuracy of a method of CVC positioning, based on external topographic landmarks. DESIGN A prospective, randomized study. SETTING Universi...

Today the geoid can be conveniently determined by a set of high-degree spherical harmonics, such as EGM08 with a resolution of about 5'. However, such a series will be biased when applied to the continental geoid inside the topographic masses. This error we call the analytical downward continuation (DWC) error, which is closely related with the so-called topographic potential bias. However, whi...

Ocean simulations are in part determined by topographic waves with speeds and spatial scales dependent on bottom slope. By their very nature, discrete z-level ocean models have problems accurately representing bottom topography when slopes are less than the grid cell aspect ratio Dz/Dx. In such regions, the dispersion relation for topographic waves is inaccurate. However, bottom topography can ...

Previous studies have shown a strong correlation between topographic/soil features and agricultural production; however, linkages these insurance products are scarce. Agricultural is an ever-growing means of governmental support for producers globally. However, failure to set premiums that accurately reflect risk exposure can lead low participation rates and/or adverse selection. The U.S. feder...

This paper presents a novel approach to finding a priori interesting regions in mammograms. We propose a topographic representation called the iso-level contour map consisting of iso-level contours at multiple intensity levels, in order to delineate those regions of interest (ROI’s) in mammograms which appear to be salient. Such salient areas form a dense quasi-concentric pattern of iso-level c...

The areas covered by a river play an important role in analyzing the causes of debris flows. The damage caused by debris flows costs over a thousand million dollars in Taiwan. Usually, after natural disasters like typhoons and earthquakes have occurred, the topographic conditions are changed. How to locate these topographic changes is an important research issue for protecting people from natur...

Base-level maps (or “isobase maps”, as originally defined by Filosofov, 1960), express a relationship between valley order and topography. The base-level map can be seen as a “simplified” version of the original topographic surface, from which the “noise” of the low-order stream erosion was removed. This method is able to identify areas with possible tectonic influence even within lithologicall...

Topographic indices like the Topographic Wetness Index (TWI) have been used to predict spatial patterns of average groundwater levels and to model the dynamics of the saturated zone during events (e.g., TOPMODEL). However, the assumptions underlying the use of the TWI in hydrological models, of which the most important is that groundwater level variation can be approximated by a series of stead...

Digital terrain models (DTMs) are not commonly used to integrate for landscape spatial analysis. Two dimensional patch-corridor-matrix models are prototypes in landscape spatial ecology analysis. Previous studies have motivated ecologists to integrate terrain models in landscape analysis through 1) adjusting areas and distance calculations prior computing landscape indices; 2) designing new ind...