In addition to the generalized quadrangles arising naturally from smalldimensional symplectic, unitary, or orthogonal geometries, the only known finite examples are the following quadrangles and their duals: ones with parameters 4, 4 (where 4 = 2e > 8) or q*, 4 (where q = 22e+l > 8) due to Tits [4, p. 3041; and others with parameters q 1, q + 1 (for prime powers q) due to Hall [5] and Ahrens an...

The influence of average plasma energy E~ on the half thickness ℓ of a thin current sheet (TCS) is investigated for three cases of TCSs crossings. The value of ℓ was estimated from the magnetic field data by means of Cluster observations. The obtained scaling values for TCSs, Z~=ℓ/ρT, where ρT is the thermal Larmor radius, were compared with the scaling Zμ=22E~/T, where E~ and T are the average...

Continuous chemical investigation of the gorgonian coral Pinnigorgia sp. resulted in the isolation of two new sterols, 5α,6α-epoxy-(22E,24R)-3β,11-dihydroxy-9,11-secoergosta-7-en-9-one (1) and (22R)-acetoxy-(24ξ)-ergosta-5-en-3β,25-diol (2). The structures of sterols 1 and 2 were elucidated using spectroscopic methods. Sterol 1 displayed inhibitory effects on the generation of superoxide anions...

A new isocoumarin glycoside, 3R-(+)-5-O-[6'-O-acetyl]-α-D-glucopyranosyl-5-hydroxymellein (1), and a new phenylethanol glycoside, (-)-phenylethyl-8-O-α-L-rhamno-pyranoside (2), were isolated from the ethyl acetate extract of the fungus Xylaria sp. cfcc 87468, together with five known steroids, β-sitosterol (3), stigmast-4-en-3-one (4), ergosterol (5), (22E)-cholesta-4,6,8(14),22-tetraen-3-one (...

We present an intuitive and efficient method for modeling light propagation in layered isotropic anisotropic media, which we call the Iterated Ray Method. Considering a single layer sandwiched between semi-infinite layers, infinite reflected transmitted rays are summed to obtain effective Fresnel coefficients center layer. Thus, system can be represented as two layers with boundary. The model i...