Determination of the absolute space directions between Baker-Nunn camera stations

Synthetic simultaneous observations for determining fixed-earth oriented directions between Baker-Nunn camera station

H\"uckel--Hubbard-Ohno modeling of π\boldsymbol{\pi}-bonds in ethene and ethyne with application to trans-polyacetylene

Quantum chemistry calculations provide the potential energy between two carbon atoms in ethane (H$_3$C$-$CH$_3$), ethene (H$_2$C$=$CH$_2$), and ethyne (HC$\equiv$CH) as a function of the atomic distance. Based on the energy function for the $\sigma$-bond in ethane, $V_{\sigma}(r)$, we use the H\"uckel model with Hubbard--Ohno interaction for the $\pi$~electrons to describe the energies $V_{\sigma\pi}(r)$ and $V_{\sigma\pi\pi}(r)$ for the $\sigma\pi$ double bond in ethene and the $\sigma\pi\pi$ triple bond in ethyne, respectively. The fit of the force functions shows that the Peierls coupling can be estimated with some precision whereas the Hubbard-Ohno parameters are insignificant at the distances under consideration. We apply the H\"uckel-Hubbard-Ohno model to describe the bond lengths and the energies of elementary electronic excitations of trans-polyacetylene, (CH)$_n$, and adjust the $\sigma$-bond potential for conjugated polymers.Comment: 10 pages, 7 figures, 3 table

Geodetic research studies Final technical report

Geopotential surface measurement of ocean using altimeter dat

TSH, The Bone Suppressing Hormone

AbstractThe skeleton is a dynamic organ whose structural integrity depends on constant remodeling, controlled by many local and systemic factors. In this issue of Cell, Abe et al. (2003) identify thyroid-stimulating hormone (TSH) as an important regulator of this process