Detailed Topographic Information Research Articles

SIMULATION OF RUNOFF IN AGRICULTURALWATERSHEDS WITH TILE DRAINS USING AN EXTENDED TOPMODEL

A physically based model was used to simulate runoff in agricultural watersheds with tile drainage systems.The TOPMODEL, which is based on the detailed topographical information provided by a digital elevation model (DEM),was modified for this simulation study. Nine possible flow generation scenarios were used in the development of themodel. The model can identify the portions of the hydrograph resulting from tile flow, subsurface flow, and surface runoff.The performance of the model was tested through a calibration, sensitivity analysis and validation process. The simulatedhydrologic response was designed to produce several components of the outflow hydrograph which were associated withthe various possible flow generation scenarios. The results of this simulation study show that the model describes thephysical system well and provides a better insight into the hillslope hydrology of agricultural watersheds with subsurfacedrainage systems.

Simultaneous Height and Adhesion Imaging of Antibody-Antigen Interactions by Atomic Force Microscopy

Specific molecular recognition events, detected by atomic force microscopy (AFM), so far lack the detailed topographical information that is usually observed in AFM. We have modified our AFM such that, in combination with a recently developed method to measure antibody-antigen recognition on the single molecular level (Hinterdorfer, P., W. Baumgartner, H. J. Gruber, K. Schilcher, and H. Schindler, Proc. Natl. Acad. Sci. USA 93:3477–3481 (1996)), it allows imaging of a submonolayer of intercellular adhesion molecule-1 (ICAM-1) in adhesion mode. We demonstrate that for the first time the resolution of the topographical image in adhesion mode is only limited by tip convolution and thus comparable to tapping mode images. This is demonstrated by imaging of individual ICAM-1 antigens in both the tapping mode and the adhesion mode. The contrast in the adhesion image that was measured simultaneously with the topography is caused by recognition between individual antibody-antigen pairs. By comparing the high-resolution height image with the adhesion image, it is possible to show that specific molecular recognition is highly correlated with topography. The stability of the improved microscope enabled imaging with forces as low as 100 pN and ultrafast scan speed of 22 force curves per second. The analysis of force curves showed that reproducible unbinding events on subsequent scan lines could be measured.

Wear of cylinder bore microtopography

Atomic force microscopy (AFM) reveals additional 3D topography information on tribology surfaces previously measured and evaluated by conventional 2D stylus technologies. This paper deals with the implications of the more detailed topographical information scanned from cast iron automotive cylinder liners. Worn and unworn surfaces measured both by AFM and stylus techniques were compared visually and quantitatively using an effective relocation technique. Quantitative comparison was made of 3D and 2D surface parameters, such as root mean square roughness, and slope, significant for the tribological behaviour of the surfaces. The extra surface features found by the AFM measurements (e.g. steeper slopes and more peaks and valleys) significantly change the numerical values of the roughness parameters, and this scale-dependent difference, when compared with conventional stylus-measured parameters, points to the possibilities of deepening the understanding of cylinder liner lubrication in the light of more finely detailed measurements.

Corneal Topography using a New Moiré Image-based System

Aim: To describe a new device, the Maastricht topographer (MT), which uses the principle of moire interference, to measure corneal shape. Methods: The Maastricht Topographer (MT) projects two sinewave gratings onto the tearfilm in quick succession, and by local analysis of grating intensity in the image so formed, reconstructs the true corneal shape in terms of height from a reference plane. A total of 262 144 data points are measured in an area 21.5 × 14.5 mm. During a one year period, patients referred for topography had measurements made by the MT and a videokeratoscope. Three cases were selected to demonstrate the advantages of the MT. Results: Image acquisition by the MT was straightforward, with alignment and focusing being of less importance than in videokeratoscopes. It provided detailed topographic information from the whole corneal area, and from irregular or non-reflective surfaces. The initial reconstruction of the true corneal shape was expressed in terms of height, from which measurements of slope, curvature and power were derived directly. Conclusions: Height reconstructions made by the MT are particularly useful in certain corneal pathologies and in evaluating the corneal profile after photorefractive keratectomy. Measurement of the ablation surface immediately postoperatively is essential in the study of ablation profiles and postoperative wound healing.

A distributed model for real-time flood forecasting using digital elevation models

A distributed model for real-time rainfall-runoff simulation during floods is presented. The model, called Distributed Basin Simulator (DBSIM) is based on the detailed topographical information provided by Digital Elevation Models (DEM). Basin representation uses the rectangular grid of the DEM. Soil properties, input data and state variables are also represented as data layers using the same scheme. Distributed rainfall input is used to map the topographically driven evolution of saturated areas as the storm progresses. The model applies a kinematic model of infiltration to evaluate local runoff generation in grid elements and accounts for lateral moisture flow between elements and surface flow routing in a simplified manner. Model performance is evaluated through sensitivity analyses and an exercise of model calibration and verification.

Tower gravity experiment: No evidence for non-Newtonian gravity

A test of Newton's inverse-square law of gravitation by Eckhardt, Jekeli, Lazarewicz, Romaides, and Sands using gravity measurements on a tall tower yielded evidence for non-Newtonian gravity. We have refined the analysis of that experiment by including detailed topographic information and conclude that, in fact, no such evidence exists. The accuracy of the experiment constrains the Yukawa-potential coupling constant \ensuremath{\alpha} to be less than 0.001.

Ribonucleic acid-protein cross-linking within the intact Escherichia coli ribosome, utilizing ethylene glycol bis[3-(2-ketobutyraldehyde) ether], a reversible, bifunctional reagent: identification of 30S proteins.

To obtain detailed topographical information concerning the spatial arrangement of the multitude of ribosomal proteins with respect to specific sequences in the three RNA chains of intact ribosomes, a reagent capable of covalently and reversibly joining RNA to protein has been synthesized [Brewer, L.A., Goelz, S., & Noller, H. F. (1983) Biochemistry (preceding paper in this issue)]. This compound, ethylene glycol bis[3-(2-ketobutyraldehyde) ether] which we term "bikethoxal", possesses two reactive ends similar to kethoxal. Accordingly, it reacts selectively with guanine in single-stranded regions of nucleic acid and with arginine in protein. The cross-linking is reversible in that the arginine- and guanine-bikethoxal linkage can be disrupted by treatment with mild base, allowing identification of the linked RNA and protein components by standard techniques. Further, since the sites of kethoxal modification within the RNA sequences of intact subunits are known, the task of identifying the components of individual ribonucleoprotein complexes should be considerably simplified. About 15% of the ribosomal protein was covalently cross-linked to 16S RNA by bikethoxal under our standard reaction conditions, as monitored by comigration of 35S-labeled protein with RNA on Sepharose 4B in urea. Cross-linked 30S proteins were subsequently removed from 16S RNA by treatment with T1 ribonuclease and/or mild base cleavage of the reagent and were identified by two-dimensional polyacrylamide gel electrophoresis. The major 30S proteins found in cross-linked complexes are S4, S5, S6, S7, S8, S9 (S11), S16, and S18. The minor ones are S2, S3, S12, S13, S14, S15, and S17.

Ultrasound gray‐scale pattern and guided aspiration puncture of abdominal abscesses

Various ultrasound gray-scale patterns of 45 consecutive abscesses were studied in 43 surgical and medical patients. Eleven abscess formations were unsuspected clinically, 27 had developed as a postoperative complication; 25 collections (55.6%) presented with an anechoic appearance, and 15 (33.3%) showed a mainly fluid pattern but contained a few nonreverberatory echoes. Five abscesses (11.1%) appeared with a complex solid-like pattern with large amounts of internal echoes. A total of 28 ultrasound guided diagnostic fine-needle aspirations of abscesses were performed on 26 patients without serious complications. All the aspirated samples yielded material sufficient for cytological or bacteriological examinations. Percutaneous fine-needle aspiration guided by sonography is recommended as a safe and useful diagnostic measure to confirm the nature of an ultrasonically displayed abdominal lesion suspected to be an abscess. Results from both sonography and confirmatory aspiration provide detailed topographic and diagnostic information for the choice of surgical or nonoperative management of abdominal abscess.