Reduction of open membrane moduli

We perform a general reduction of the open membrane metric in a worldvolume direction of the M5-brane. Using reduction rules analogous to the bulk, we show that the open membrane metric leads to the standard open string metric and open string coupling constant on the D4-brane only for an ``electric'' reduction in which case the open membrane metric has no off-diagonal components and the Born-Infeld curvature tensor is a matrix of rank 2. Instead, if we perform a general reduction, with nonzero off-diagonal components of the open membrane metric, we obtain a rank 4 Born-Infeld tensor corresponding to a bound state of an open string with an open D2--brane. Next, we identify and reduce a 3-form open membrane ``noncommutativity'' tensor on the M5-brane. This open membrane parameter only reduces to the open string noncommutativity tensor on the D4-brane provided we constrain ourselves to an ``electric'' or a ``magnetic'' reduction.Comment: 15 pages, LaTeX, uses JHEP.cls and JHEP.bst style file

Electrical properties of basalts from Sites 768 and 770

Journal ArticleConductivity of 54 basalt samples from ODP Sites 768 and 770 was measured as a function of temperature and fluid salinity. Porosity was also measured for all samples, and cation exchange capacity was measured for 46 of the samples. Porosity measurements indicated that porosity is underestimated for basalts like these, unless one uses extensive drying at high vacuum. At salinities greater than 29 ppt, and throughout the range of salinity and temperatures likely in situ, sample conductivity (Co) is controlled by porosity () according to the Archie relation Co = 0.22-C^?13 (orFF = 4.5//1.3), where Cw is conductivity of the pore fluids and FF = CJCO is the formation factor. At lower salinity, clay-surface conduction or microcrack conduction may dominate. We are unable to distinguish reliably between the two mechanisms, but we do detect their effects subtly at high salinity and strongly at low salinity