The dehydration, rehydration and tectonic setting of greenstone belts in a portion of the northern Kaapvaal Craton, South Africa

High-grade gneiss terranes and low-grade granite-greenstone terranes are well known in several Archaean domains. The geological relationship between these different crustal regions, however, is still controversial. One school of thought favors fundamental genetic differences between high-grade and low-grade terranes while others argue for a depth-controlled crustal evolution. The detailed examination of well-exposed Archaean terranes at different metamorphic grades, therefore, is not only an important source of information about the crustal levels exposed, but also is critical to the understanding of the possible tectonic and metamorphic evolution of greenstone belts with time. Three South African greenstone belts are compared

Quantitative Analysis of Particulate Burden in Lung Tissue

Numerous methods have been used in the preparation and analysis of the particulate matter deposited in human lungs. Preparation techniques include those for particle isolation and for in situ analysis. Analytical techniques include bulk and particle-by-particle analysis. In this paper, a general discussion of many of these methods is presented along with examples of how two specific techniques have been used. In one study, individual particles from the lungs of 75 randomly selected autopsy cases were analyzed using an automated scanning electron microscopy (SEM)/ energy dispersive X-ray microanalysis (EDX) system. An average of 613 million particles, of exogenous origin, per gram of dry lung tissue were found, the major classes of particles being silica, talc, aluminum silicates, and rutile. In the second study, lungs from 50 randomly selected autopsy cases were analyzed using gravimetric and X-ray diffraction (XRD) analysis. The median total particulate material was 0.33 grams, for cases in which samples were prepared by high temperature ashing, and 0.41 grams, for those in which nitric acid digestion was used. The median amount of quartz for all cases, was 0.044 grams. Samples of eighteen of the 75 lungs previously analyzed by automated SEM/EDX were also analyzed using gravimetric and XRD analysis. A good correlation was seen between the results of the two procedures (r=0.91 for number of exogenous particles versus grams of particulate matter and r=0.97 for number of silica particles versus amount of quartz)

Physical Electronics

Contains reports on four research projects

Physical Electronics

Contains reports on three research projects

Lung Particulate Burdens of Subjects from the Cincinnati, Ohio Urban Area

Because of the relatively small data base existing for lung particulate burdens of subjects with no overt pneumoconioses, the total exogenous lung particulate concentrations of 91 subjects from the Cincinnati, Ohio urban area were determined using an automated scanning electron microscope-energy dispersive x-ray analysis-image analysis system. Four of these subjects were foundry workers and had the highest exogenous particle concentrations seen in the 91 lungs, ranging from 1860 to 2990 x 106 particles per gram of dry lung (ppg). The average exogenous particle concentration for the remaining 87 subjects was 476 ± 380 x 106 ppg with a range of 71 to 1860 x 106 ppg. The median size of the exogenous particles in the 87 lungs was narrow, ranging from 0.37 to 1.02 µm. The geometric mean particle size over all 87 lungs was 0.60 µm with a geometric standard deviation (σg) of 2.35. The total exogenous particle levels were elevated for the male subjects compared to females (p=0.015), and were positively associated with age (p=0. 021). However, no correlation was seen between total particle concentration and race or smoking history

An Automated Machine-Learning Approach for Road Pothole Detection Using Smartphone Sensor Data.

Road surface monitoring and maintenance are essential for driving comfort, transport safety and preserving infrastructure integrity. Traditional road condition monitoring is regularly conducted by specially designed instrumented vehicles, which requires time and money and is only able to cover a limited proportion of the road network. In light of the ubiquitous use of smartphones, this paper proposes an automatic pothole detection system utilizing the built-in vibration sensors and global positioning system receivers in smartphones. We collected road condition data in a city using dedicated vehicles and smartphones with a purpose-built mobile application designed for this study. A series of processing methods were applied to the collected data, and features from different frequency domains were extracted, along with various machine-learning classifiers. The results indicated that features from the time and frequency domains outperformed other features for identifying potholes. Among the classifiers tested, the Random Forest method exhibited the best classification performance for potholes, with a precision of 88.5% and recall of 75%. Finally, we validated the proposed method using datasets generated from different road types and examined its universality and robustness

Microwave Spectroscopy

Contains research objectives and reports on four research projects.Signal Corps Contract DA36-039-sc-7489

Design and Development of the LEDA Slow Wire Scanner Profile Measurement

The Low Energy Demonstration Accelerator (LEDA) [1, 2] is being developed at Los Alamos National Laboratory as part of the Accelerator Production of Tritium (APT) project. One of the diagnostics being developed to commission LEDA [3] is a slow wire scanner beam profile measurement. Initial profile measurements will be made at 6.7 MeV beam energy and 100 mA beam current. The wire scanner is an interceptive device that will move two silicon carbide coated graphite mono-filament fibers (wires) through the beam, in order to obtain the profile. Some of the design considerations discussed are; Mechanical design, wire temperature analysis, secondary electron detection, signal processing, and system control

Gravity Evidence for a Larger Limpopo Belt in Southern Africa and Geodynamic Implications

The Limpopo Belt of southern Africa is a Neoarchean orogenic belt located between two older Archean provinces, the Zimbabwe craton to the north and the Kaapvaal craton to the south. Previous studies considered the Limpopo Belt to be a linearly trending east-northeast belt with a width of ∼250 km and ∼600 km long. We provide evidence from gravity data constrained by seismic and geochronologic data suggesting that the Limpopo Belt is much larger than previously assumed and includes the Shashe Belt in Botswana, thus defining a southward convex orogenic arc sandwiched between the two cratons. The 2 Ga Magondi orogenic belt truncates the Limpopo-Shahse Belt to the west. The northern marginal, central and southern marginal tectonic zones define a single gravity anomaly on upward continued maps, indicating that they had the same exhumation history. This interpretation requires a tectonic model involving convergence between the Kaapvaal and Zimbabwe cratons during a Neoarchean orogeny that preserved the thick cratonic keel that has been imaged in tomographic models