Nickel hydrogen capacity loss

The results of tests to assess capacity loss in nickel hydrogen cells are presented in outline form. The effects of long storage (greater than 1 month), high hydrogen pressure storage, high cobalt content, and recovery actions are addressed

Immersed and virtually embedded pi_1-injective surfaces in graph manifolds

We show that many 3-manifold groups have no nonabelian surface subgroups. For example, any link of an isolated complex surface singularity has this property. In fact, we determine the exact class of closed graph-manifolds which have no immersed pi_1-injective surface of negative Euler characteristic. We also determine the class of closed graph manifolds which have no finite cover containing an embedded such surface. This is a larger class. Thus, manifolds M^3 exist which have immersed pi_1-injective surfaces of negative Euler characteristic, but no such surface is virtually embedded (finitely covered by an embedded surface in some finite cover of M^3).Comment: Published by Algebraic and Geometric Topology at http://www.maths.warwick.ac.uk/agt/AGTVol1/agt-1-20.abs.htm

Observations of cometary parent molecules with the IRAM radio telescope

Several rotational transitions of HCN, H2S, H2CO, and CH3OH were detected in comets P/Brorsen-Metcalf 1989 X, Austin (1989c1) and Levy (1990c) with the Institute for Millimeter Radioastronomy (IRAM) 30-m radio telescope. This allows us to determine the production rates of these molecules and to probe the physical conditions of the coma

The correlation between water production rates and visual magnitudes in comets

From the visual magnitudes of the International Comet Quarterly data base and the OH radio lines measured at the Nancay radio telescope, the law log Q(H2O) = 30.74 (+/-0.02) - 0.240 (+/-.003) m(sub h) is derived from a sample of 13 comets

Enhancement of superconductive critical temperatures in almost empty or full bands in two dimensions: possible relevance to beta-HfNCl, C60 and MgB2

We examine possibility of enhancement of superconductive critical temperature in two-dimensions. The weak coupling BCS theory is applied, especially when the Fermi level is near the edges of the electronic bands. The attractive interaction depends on ${\bf k}$ due to screening. The density of states(DOS) does not have a peak near the bottom of the band, but $k$-dependent contribution to DOS (electron density on the Fermi surface) has a diverging peak at the bottom or top. These features lead to significant enhancement of the critical temperatures. The results are qualitatively consistent with the superconductive behaviors of HfNCl (\Tc \le 25K) and ZrNCl(\Tc \le 15K), C$_{60}$ with a field-effect transistor configuration (\Tc = 52K), and MgB$_2$ (\Tc \approx 40K) which have the unexpectedly high superconductive critical transition temperatures.Comment: 5 pages,4 figure