Approach to a rational rotation number in a piecewise isometric system

We study a parametric family of piecewise rotations of the torus, in the limit in which the rotation number approaches the rational value 1/4. There is a region of positive measure where the discontinuity set becomes dense in the limit; we prove that in this region the area occupied by stable periodic orbits remains positive. The main device is the construction of an induced map on a domain with vanishing measure; this map is the product of two involutions, and each involution preserves all its atoms. Dynamically, the composition of these involutions represents linking together two sector maps; this dynamical system features an orderly array of stable periodic orbits having a smooth parameter dependence, plus irregular contributions which become negligible in the limit.Comment: LaTeX, 57 pages with 13 figure

The influence of defects of the fatigue resistance of butt and girth welds in A106B steel

This three-phase study was directed at developing a fitness for service defect acceptance criteria for welds with defect indications. The study focussed on A106 Gr. B steel pipe. The first phase involved a literature search and critical review to develop the preliminary acceptance criteria to the extent permitted by the data. The second phase developed data for flat plate, wall segment, and vessel specimens containing artificial or natural planar or volumetric defects. The final phase developed acceptance criteria from the test data

Density and conductivity of bismuth single crystals grown in magnetic fields with relation to their mosaic structure

In continuation of the study of the thermoelectric effect, previously described by Goetz and Hasler, existing between the two halves of the same bismuth single crystal, of which one has been crystallized within, and the other outside of a strong magnetic field (21,000 gauss), the density and the specific resistance of different sections of these crystals, grown by the discontinuous method, have now been measured. The change of density of "magnetic" crystals. The density of perfect crystals grown under normal conditions was found to be between 9.82 and 9.83 i.e., 0.2 percent higher than the values of other authors. Furthermore, it was found that any crystalline imperfection such as twinning, etc., decreases the density; that, further there exists a difference of density between the "normal" and the "magnetic" half of the same crystal, the sign of which depends on the orientation with which the crystal entered the field: In case the trigonal axis is normal to the axis of the rod and normal to the lines of force, the "magnetic" half shows an increase of density, whereas the opposite is true in case the principal axis is parallel to the rod (and therefore parallel to the direction of growth and to the heat-flow). The difference of density is ca. 0.3 percent but can be several percent in imperfect crystals. The purity of the metal affects the change of the density. The results indicate that the ideally pure metal would not be affected by the magnetic treatment. The specific resistance of "magnetic" crystals. The values of the specific resistance obtained on "normal" single crystals agree approximately with the results obtained by Bridgman and Kapitza and also with those obtained by spectroscopic analysis. The value of ρ∥/ρ⊥ was found to be much larger for bismuth, being sensitive to the "magnetic" treatment. There is a small change of resistance between the normal and the magnetic half, depending on the orientation of the crystal to the field. In case the orientation is such as to decrease the density the resistance increases and vice versa. The accuracy necessary for the satisfactory quantitative determination of the change could not yet be reached, since the change is of the magnitude of 0.5 percent. An attempt is made to combine the phenomena of the magnetic effect thus far known. It seems probable that the influence of the magnetic field upon the formation of a crystal consists of a change within the mosaic structure of the lattice. The investigation is being continued

Calibration of the LIGO displacement actuators via laser frequency modulation

We present a frequency modulation technique for calibration of the displacement actuators of the LIGO 4-km-long interferometric gravitational-wave detectors. With the interferometer locked in a single-arm configuration, we modulate the frequency of the laser light, creating an effective length variation that we calibrate by measuring the amplitude of the frequency modulation. By simultaneously driving the voice coil actuators that control the length of the arm cavity, we calibrate the voice coil actuation coefficient with an estimated 1-sigma uncertainty of less than one percent. This technique enables a force-free, single-step actuator calibration using a displacement fiducial that is fundamentally different from those employed in other calibration methods.Comment: 10 pages, 5 figures, submitted to Classical and Quantum Gravit

Lasalocid Sodium Supplementation For Grazing Steers

Lasalocid sodium (Bovatec) is a feed additive which has been reported to promote growth and improve feed utilization by cattle. The product appears to function by stimulating a more favorable and efficient microbial fermentation of the feed, thus improving rate and efficiency of production. Other research has also indicated the product to be an effective coccidiostat for cattle. A previous experiment (CATTLE 80-10) with feedlot steers fed a high-grain ration resulted in 4.3% greater gains with 8.3% less feed (ADG , 3.23 lb. with 7.63 lb. feed per 1b. gain for the control group). In the experiment reported here, lasalocid was tested for its effects on weight gain of grazing steers. The product was fed at two levels and compared to a nonmedicated control and to monensin (Rumensin)

The detection of geothermal areas from Skylab thermal data

Skylab-4 X-5 thermal data of the geysers area was analyzed to determine the feasibility of using midday Skylab images to detect geothermal areas. The hottest ground areas indicated on the Skylab image corresponded to south-facing barren or sparsely vegetated slopes. A geothermal area approximately 15 by 30 m coincided with one of the hottest areas indicated by Skylab. This area could not be unambiguously distinguished from the other areas which are believed to be hotter than their surroundings as a result of their topography, and micrometeorological conditions. A simple modification of a previous thermal model was performed and the predicted temperatures for the hottest slopes using representative values was in general agreement with the observed data. It is concluded that data from a single midday Skylab pass cannot be used to locate geothermal areas

Ten year change in forest succession and composition measured by remote sensing

Vegetation dynamics and changes in ecological patterns were measured by remote sensing over a 10 year period (1973 to 1983) for 148,406 landscape elements, covering more than 500 sq km in a protected forested wilderness. Quantitative measurements were made possible by methods to detect ecologically meaningful landscape units; these allowed measurement of ecological transition frequencies and calculation of expected recurrence times. Measured ecological transition frequencies reveal boreal forest wilderness as spatially heterogeneous and highly dynamic, with one-sixth of the area in clearings and early successional stages, consistent with recent postulates about the spatial and temporal patterns of natural ecosystems. Differences between managed forest areas and a protected wilderness allow assessment of different management regimes