Anhysteretic remanent magnetization (ARM) in magnetite grains

Summary ARM has been measured in a range of inducing, steady fields up to 50 oersteds and for 6 sizes of magnetite grains with average diameters 5 m to 174 m. For all sizes a slight non-linearity of ARM with inducing field was found, apparently comprising a non-linear contribution independent of grain size plus a linear contribution which increased with decreasing grain size. In the largest grains induced ARM agreed well with multidomain grain theory. Relative enhancement of ARM in smaller grains is comparable to the enhancement of thermoremanence and therefore appears to indicate a pseudosingle domain contribution to ARM in small grains. However the observations allow an alternative explanation in terms of more extreme dimension ratios in the smaller grains. Presentation of the equations for multidomain ARM and TRM using observed instead of intrinsic susceptibilities makes it appear that the inadequacy of multidomain theory (and consequent necessity for pseudo-single domain theory) are less serious than has been supposed.     

Intensive infiltrometer studies on a plowed big sagebrush site

Intensive infiltrometer studies were made over a 4-year period on a plowed big sagebrush (Artemisia tridentata) site in southern Idaho. Results of the study indicate there was a natural decay in absorptive capabilities of surface soils due to the plowing treatment. The apparent result of grazing was not to reduce the minimal infiltration capacities measured on the respective site, but rather to eliminate seasonal trends so that infiltration rates were at the low end of the scale throughout the year. Grazing did not increase sediment production potentials beyond the increases expected as a result of mechanical disturbance associated with plowing. Attempts at predicting infiltration rates and potential sediment production indicated that easily measured soil cover characteristics do not adequately reflect the potential (actual) hydrologic performance of a big sagebrush site which has been grossly modified by activity such as plowing or grazing.     

Interference of oil spill emulsifiers with gas chromatography

Several commercially available spill control agents interfere with gas chromatographic correlation of spilled oils with suspected sources. The effects of four such products are presented. Two of these interfere seriously. One is removable by a simple clean-up procedure, and the other is not removable in principle. In favourable cases, its interference may be minimized by extrapolation. Anticipated interference with other analytical methods is surveyed.     

Toward green cartography & visualization: a semantically-enriched method of generating energy-aware color schemes for digital maps

ABSTRACT

We introduce a semantically-enriched method of generating color schemes for various types of digital maps that reduces the energy consumption of the display device while preserving the quality of the original design. Energy-aware design intersects two important trends in cartography. First, as more maps are viewed today on mobile, battery life has become a central constraint influencing design. Second, there is increasing need for green computing, which encourages the efficient use of energy to limit environmental impacts. This paper focuses on one important aspect of energy-aware cartography: color design. Existing research on energy-aware color adjustment methods apply broadly to images or websites. However, the colors used in maps have more structured semantic relationships than most documents viewed on mobile devices, and efforts to account for these relationships while reducing energy consumption are limited. To fill this gap, we mathematically formalize energy-aware map-color adjustment as a constrained optimization problem: we define energy consumption as the objective function and model the preservation of semantic relationships as the search constraints. We evaluate our proposed method against a common color dimming method using four maps with different semantic relationships. The evaluation suggests that our proposed method better preserves the original color semantics.     

Natural geobatteries associated with sulphide ore deposits,I. Theoretical studies

Any conductive sulphide ore body can generate electrical ore potentials and this can be regarded as a geobattery, with an upper positive cathode and a lower negative anode. Two mechanisms which can occur simultaneously and which appear to explain these potentials are the oxygen concentration cell (OCC) and the sulphide galvanic cell (SGC). When there is a difference of O₂ concentration between the cathode and anode, the OCC operates by contributing oxygen to the anode, and ceases when the difference is diminished. However, gradients of pH, temperature or pressure can keep the cell operating. In the SGC the sulphides dissolve at the anode (producing metal ions, sulphur and electrons), while at the cathode, either sulphides dissolve producing metal and sulphur ions, or reaction is as in the OCC. The ore potential measured in the field is the sum of the oxygen concentration cell and at times locally dominant sulphide galvanic cells.