COMMUTING DISTANCE AND GENDER AMONG NONMETROPOLITAN UNIVERSITY EMPLOYEES*

The applicability of metropolitan-derived explanations of gender differences in worktrip lengths is examined based on a sample of 435 university employees in the nonmetropolitan town of Blacksburg, VA. Women's worktrips are found to be longer than men's in contrast to metropolitan findings. This pattern results from the interaction of spatial structures of housing and employment with women's lower incomes, gender segregation of employment, and the tendency for married women to find jobs after their residence is established. Upward trends in female labor force participation rates and in nonmetropolitan growth require continued analysis of their joint impact on women's spatial behavior.     

Relatively stable,large-amplitude Alfvénic waves seen at 2.5 and 5.0 AU

Pioneer 11 and 10 observations of the wave structure seen in a corotating interaction region at 2.5 AU on day 284 of 1973 and 8 days later at 5 AU reveal large-amplitude Alfvénic structures with many detailed correlations seen between their features at the two radial distances. Hodogram analysis suggests the dominance of near plane polarized, transverse Alfvénic mode fluctuations with periods between 2 min and one hour or more. Some wave evolution close to the Corotating Interaction Region (CIR) shock is noticed, but waves towards the centre of the compression seem to propagate with little damping between the spacecraft observation positions.     

Frame-invariance of turbulence constitutive relations

The applicability of the principle of material frame-indifference to turbulence and its consequences for turbulence modelling are considered. By introducing a distinction between arbitrary time-dependent orthogonal transformations of (i) the fluid motion, and (ii) the observer, we find that frame-invariant tensorial measures of the absolute angular velocity and acceleration can be defined. This follows from consideration of a four-dimensional formulation of classical mechanics which formally possesses the property of invariance under arbitrary changes of frame of the observer. These tensors allow the construction of constitutive equations which depend, for example, on the absolute angular velocity of the fluid, and which also satisfy the principle of material frame-indifference. The results of this analysis have application outside the field of turbulence modelling. The invariance properties of some previously published Reynolds stress transport turbulence models are examined and modifications are suggested.     

Simulation of groundwater flow and contaminant transport at a landfill site using models

Numerical and analytical modelling studies were conducted for the analysis of groundwater flow and contaminant transport at the Innisfil landfill site in the Town of Innisfil, County of Simcoe, in Ontario, Canada. Previously conducted field studies categorized the upper stratigraphy at the site into three units: upper sand unit, upper silt/clay unit and Intermediate Sand unit. Essentially horizontal groundwater movement in the two sand units and vertical downward flow in the silt/clay unit were reported by the field hydrogeologists. In the following, application of three computer models (FLOWPATH, USGS MOC and POLLUTE) for the simulation of the groundwater flow and contaminant transport processes at the Innisfil landfill site is described. The paper focuses on the calibration of groundwater flow and contaminant transport systems, and demonstrates how the insight gained during the contaminant transport calibration was used to improve the initial groundwater flow characterization of the hydrogeological system.     

Effect of groundwater interception and irrigation on salinity and piezometric levels of an aquifer

The major strategy used to prevent the discharge of highly saline groundwater to the River Murray in southeastern Australia is groundwater interception and disposal. The basic design principle assumes that the extraction of groundwater from an aquifer hydraulically connected to the river, using a line of pumps positioned close and roughly parallel to the river, will decrease piezometric heads thereby reducing the discharge of saline groundwater to the river. The paper considers one of these schemes which was designed for the Mildura area on the basis of a hydrogeological investigation. It analyses the effects on piezometric head and groundwater salinity due to the groundwater interception scheme and adjacent irrigation activity over a period of several years from January 1980. It is shown that piezometric heads have decreased significantly in the stretch close to the river. A slight reduction in groundwater salinity is also apparent in this stretch except for an area between the river and a holding basin used for disposal of the saline effluents emanating from the groundwater interception scheme. This general reduction in groundwater salinity is mainly caused by pumping from the groundwater interception scheme and recharge from irrigation. The exception in the trend in groundwater salinity is due to the movement of a highly saline body of groundwater from the holding basin towards the River Murray. Results of this Australian experience should be helpful to the designers of similar salinity mitigation schemes elsewhere.     

Magneto-atmospheric waves from a localized source

A technique developed by Lighthill for finding the asymptotic solution of an inhomogeneous wave equation with constant coefficients is applied to the study of wave propagation in magneto-atmospheres. The geometry of the wave number surface plays an important role in determining the generation and propagation of various types of magneto-atmospheric waves from a localized forcing region. Examples of these wavenumber surfaces are exhibited for various magnetic field strengths and wave frequencies. The asymptotic far field is tabulated for a time-harmonic, spatially gaussian, localized forcing term.     

40Ar-39Ar Ages of Types 3 and 4, L and H Chondrites from Antarctica

Abstract— This is a report on ⁴⁰Ar-³⁹Ar studies of 7 low petrographic type L and H chondrites from Antarctica. From petrographic similarities it has been argued that the L3 chondrites ALHA77015, ?77167, ?77249, and ?77260 are pieces from a common fall (McKinley et al., 1981). Our results now confirm this supposition: The four meteorites have identical characteristic Ar-degassing patterns, very similar K, Ca, Cl, and ³⁶Ar_trapped contents, and similar ⁴⁰Ar-³⁹Ar ages of <4 Ga which are rather unusual for ordinary chondrites and might be due to shock. The undulating age patterns could be due to weathering or to ³⁹Ar recoil. The L4 chondrite ALHA77230 shows no age plateau and only a lower limit for the time of a severe degassing, 4.0 Ga, can be given. ALHA77226 and RKPA78002, two H4 chondrites, exhibit reasonably well defined age plateaus at about 4.3 and 4.4 Ga. Two individual chondrules from RKPA78002 have the same age as the whole rock sample.