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Body density (Db) of 54 boys and girls 10–18 years of age (13.9 ± 2.4 years) was measured in an air-displacement plethysmograph, the BOD POD®, and compared to Db determined by hydrodensitometry (HW). Both Db values were converted to percent body fat (%BF) using a two-component model conversion formula and compared to %BF determined by dual energy X-ray absorptiometry (DXA). Body density estimated from the BOD POD (1.04657 ± 0.01825 g/cc) was significantly higher than that estimated from HW (1.04032 ± 0.01872 g/cc). The relative body fat calculated from the BOD POD (23.12 ± 8.39 %BF) was highly correlated but, on average, 2.9% BF lower than %BF DXA. Average %BF estimates from HW and DXA were not significantly different. Despite consistently underestimating the %BF of children, the strong relationship between DXA and the BOD POD suggests that further investigation may improve the accuracy of the BOD POD for assessing body composition in children.

The double-shearing model of flow attributes plastic deformation in granular materials to cooperative slip on conjugate Coulomb shears (surfaces upon which the Coulomb yield condition is satisfied). The strict formulation of the double-shearing model then requires that the slip lines in the material coincide with the Coulomb shears. Three different experiments that approximate simple shear deformation in granular media appear to be inconsistent with this strict formulation. For example, the orientation of the principal stress axes in a layer of sand driven in steady, simple shear was measured subject to the assumption that the Coulomb failure criterion was satisfied on some surfaces (orientation unspecified) within the sand layer. The orientation of the inferred principal compressive axis was then compared with the orientations predicted by the double-shearing model. The strict formulation of the model [Spencer, 1982] predicts that the principal stress axes should rotate in a sense opposite to that inferred from the experiments. A less restrictive formulation of the double-shearing model by de Josselin de Jong [1971] does not completely specify the solution but does prescribe limits on the possible orientations of the principal stress axes. The orientations of the principal compression axis inferred from the experiments are probably within those limits. An elastoplastic formulation of the double-shearing model [de Josselin de Jong, 1988] is reasonably consistent with the experiments, although quantitative agreement was not attained. Thus we conclude that the double-shearing model may be a viable law to describe deformation of granular materials, but the macroscopic slip surfaces will not in general coincide with the Coulomb shears.

Permeability, porosity, and volumetric strain measurements were conducted on granite cores obtained at depths of 0.7 to 1.6 km from the Illinois UPH 3 drillhole at effective confining pressures from 5 to 100 MPa. Initial permeabilities were in the range of 10−17 to 10−19 m2 and dropped rapidly with applied pressure to values between 10−20 and 10−24 m2 at 100 MPa, typical of other deep granite core samples. These values are several decades lower than equivalent weathered surface granites at comparable effective confining pressures, where weathering products in cracks and pores inhibit crack closure with applied pressure. Permeabilities of the Illinois cores were inversely related to sample depth, suggesting that stress relief and thermal microfractures induced during core retrieval dominated the fluid flow. Thus these samples provide an upper bound on in situ matrix permeability values. A comparison of core permeability from UPH 3 and other deep drillholes shows that stress relief damage can often dominate laboratory permeability measurements. We conclude that it may be difficult to make meaningful estimates of in situ permeability based on either borehole samples (possible damage during retrieval) or surface-derived analogs (altered by weathering). Volumetric strain determined from porosity measurements was compared with differential strain analysis (DSA) data reported by other investigators on samples from the same depths in the drillhole. Our strain measurements (0.002 to 0.005 at 100 MPa) were nearly twice as large as the DSA values, probably because of the crack-enhancing effects of fluids present in our samples that are absent in the dry DSA cores, as well as other time-dependent deformation effects. This difference in observed strain magnitudes between the two measurement methods may be an important consideration if strain and/or porosity data from deep core samples are used in models of stress, fluid circulation, and excess fluid pressure generation in the midcrust.

Laboratory tests reveal that the permeabil- ity of samples obtained from deep boreholes is often lower and more sensitive to pressure than the perme- ability of common surface-derived crystalline rocks re- potled in the literature. We attribute the differences in permeability behavior to the fact that surface rocks have histories of unloading, weathering and retrograde metamorphism which are not comparable to that of the deeper rocks. Weathering products that line cracks and pores of surface rocks and make these openings more difficult to close as pressure increases may account for the relatively low pressure-sensitivity of permeability. Stress-relief cracking in the borehole samples can also reduce the pressure sensitivity. These results have im- portant implications for models that incorporate as- sumptions about the transport properties of rock at depth, such as models of heat transport or fluid pressure buildup, because many models are based on the prop- erties of common surface-derived rocks. Other physi- cal properties that are controlled by cracks and pores, such as seismic velocity and electrical resistivity, may be similarly affected by differences between surface-derived and deep rocks.

Fortification of enriched grains with synthetic folic acid is a potential concern for the elderly population who is at higher risk for Vitamin B12 deficiency. Consuming excess amounts of naturally occurring folate or synthetic folic acid can precipitate a deficiency of Vitamin B12, resulting in neurological damage. The purpose of this study was to determine the increase in folate intake in an elderly population due to the fortification of enriched grains. Three-day diet records of 320 participants (average age 76.8 years) were evaluated for total folate intake from food and supplements before and after the fortification of enriched grains. There was a significant mean daily folate intake increase of 63.8 microg due to fortification (p0.0001), raising the intake of total folate to 359 microg (89.8% of RDA). Supplements containing folic acid were consumed by 66% of the participants, raising the average total folate intake of supplement users to 793 microg per day. Only 5 participants exceeded the UL of 1,000 microg folic acid per day, with all 5 of these individuals consuming more than 1,000 microg folic acid per day from supplements alone. Folic acid fortification of grains does not appear to have increased the risk of excess folic acid in this population.

Locations and velocities were calculated for microseisms occurring in samples of rock subjected to triaxial loading and injection of pore fluid. This was accomplished by analyzing arrival times of acoustic emission using an automatic first arrival picker. Apparent velocity anomalies were observed prior to both failure of intact samples and violent slip in samples containing saw cuts. Further analysis revealed that these fluctuations in calculated velocity were not due to changes in the true seismic velocity. Instead, variations in calculated velocity are shown to be related to sampling errors in picking first arrivals. The systematic picking of late first arrivals for small magnitude events was found to be a persistent bias resulting in low calculated velocities. This has encouraged the reexamination of earthquake records to determine how important sampling biases are in contributing to reported velocity anomalies.