The basal slip systems of biotite and their mechanical expressions have been investigated by shortening single crystals oriented to maximize and minimize shear stresses on (001). Samples loaded at 45 ø to (001) exhibit gentle external rotations associated with dislocation glide. High-angle kink bands in these samples, unlike those developed in micas loaded parallel to (001), are limited to sample comers. Samples shortened pertxmdicular to (001) show no evidence of nonbasal slip and fail by fracture over all conditions tested. The mechanical respome of biotite shortened at 45 ø to (001) is nearly perfectly elastic-plastic; stress-strain curves are characterized by a ste• elastic slope, a sharply deemed yield point, and continued deformation at low (mostly < 100 MPa), relatively constant stresses at strains >1%. Stresses measured beyond the yield point are insensitive to conf'ming pressure over the range 200 to 500 MPa and exhibit weak dependencies upon strain.. rare and ten3•a•e. Assuming an exponential relationship between differential stress c•a and strain rate oe of the form oe = C exp (otC•d) exp (-Q/RT), the data collected over strain rates and temperatures of 10-7 to 10-4 s-1 and 20 ø to 400øC, respectively, are best fit by an exponential constant ct of 0.41 q' 0.08 MPa-1 and an activation energy Q of 82 + 13 lcJ/mol. A power law fits the dam equally well with n = 18 + 4 and Q = 51 q' 9 kJ/mol. Samples oriented favorably for slip in directions [100] and [110] are measurably weaker than those shortened at 45 ø to [010] and [310], consistent with the reported Burg?rs vectors <100>, 1/2 <110>, and 1/2 <110>. The anisotropy of biotite is further revealed by contrastang these plastic strengths with results of samples deformed parallel and perpendicular to (001). Previous studies have shown that biotite loaded in the (001) plane is strong prior to the nucleation of kink bands.The strength of biotite shortened perpendicular to (001) exceeds that measured parallel to (001) and is pressure dependent. Application of the results to deformation within the continental crust suggests that biotite oriented favorably for slip is much weaker than most other silicates over a wide range of geologic conditions. Its presence within foliated rocks and shear zones may limit locally the stresses that can be supported. INTRODUCtiON Layer ,s_ilicares are weak and evidence of their deformation in •he Earths crust is widespread. The d6collements of major ttu•t sheets are commonly defined by clay-bearing shales and slams [e.g., Hayes, 1891; Rodgers, 1949; King, 1950; Chapple, 1978] and localized shear strains of mylonites and ductile shear zones are frequently associated with the presence of micas [e.g., Bell and Etheridge, 1973; Hobbs et al., 1976; White et al., 1980; Wilson, 1980; Tullis et al., 1982]. On a f'm•r scale, micas within metamorphic tectonites exhibit sharp deformation and kink bands [Hobbs et al., 1976; Wilson and Be!l, 1979; Baronnet and Olives, 1983; Vernon et al., 1983; Goodwin and Wenk, 1990], strong crystallographic ...

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[1] Using von Herzen and Maxwell's needle probe method, we measured thermal conductivity in four porous mixtures of quartz sand and methane gas hydrate, with hydrate composing 0, 33, 67 and 100% of the solid volume. Thermal conductivities were measured at a constant methane pore pressure of 24.8 MPa between À20 and +15°C, and at a constant temperature of À10°C between 3.5 and 27.6 MPa methane pore pressure. Thermal conductivity decreased with increasing temperature and increased with increasing methane pore pressure. Both dependencies weakened with increasing hydrate content. Despite the high thermal conductivity of quartz relative to methane hydrate, the largest thermal conductivity was measured in the mixture containing 33% hydrate rather than in hydrate-free sand. This suggests gas hydrate enhanced grain-to-grain heat transfer, perhaps due to intergranular contact growth during hydrate synthesis. These results for gas-filled porous mixtures can help constrain thermal conductivity estimates in porous, gas hydrate-bearing systems.

We state the benefits of transitioning from taxonomies to ontologies and ontology specification languages, which are able to simultaneously serve as recognition, reporting and correlation languages. We have produced an ontology specifying a model of computer attack using the DARPA Agent Markup Lan-guage+Ontology Inference Layer, a descriptive logic language. The ontology's logic is implemented using DAMLJessKB. We compare and contrast the IETF's IDMEF, an emerging standard that uses XML to define its data model, with a data model constructed using DAML+OIL. In our research we focus on low level kernel attributes at the process, system and network levels, to serve as those taxonomic characteristics. We illustrate the benefits of utilizing an ontology by presenting use case scenarios within a distributed intrusion detection system.

[1] Electromagnetic (EM) remote-sensing techniques are demonstrated to be sensitive to gas hydrate concentration and distribution and complement other resource assessment techniques, particularly seismic methods. To fully utilize EM results requires knowledge of the electrical properties of individual phases and mixing relations, yet little is known about the electrical properties of gas hydrates. We developed a pressure cell to synthesize gas hydrate while simultaneously measuring in situ frequency-dependent electrical conductivity (s). Synthesis of methane (CH 4 ) hydrate was verified by thermal monitoring and by post run cryogenic scanning electron microscope imaging. Impedance spectra (20 Hz to 2 MHz) were collected before and after synthesis of polycrystalline CH 4 hydrate from polycrystalline ice and used to calculate s. We determined the s of CH 4 hydrate to be 5 × 10 −5 S/m at 0°C with activation energy (E a ) of 30.6 kJ/mol (−15 to 15°C). After dissociation back into ice, s measurements of samples increased by a factor of ∼4 and E a increased by ∼50%, similar to the starting ice samples.