Luminosity Dependence in the Fundamental Plane Projections of Elliptical Galaxies

We analyze the fundamental plane projections of elliptical galaxies as a function of luminosity, using a sample of approximately 80,000 galaxies drawn from Data Release 4 (DR4) of the Sloan Digital Sky Survey (SDSS). We separate brightest cluster galaxies (BCGs) from our main sample and reanalyze their photometry due to a problem with the default pipeline sky subtraction for BCGs. The observables we consider are effective radius (R_e), velocity dispersion (sigma), dynamical mass (M_dyn ~ R_e sigma2), effective density (sigma2/R_e2), and effective surface brightness (mu_e). With the exception of the L-M_dyn correlation, we find evidence of variations in the slope (i.e. the power-law index) of the fundamental plane projections with luminosity for our normal elliptical galaxy population. In particular, the radius-luminosity and Faber-Jackson relations are steeper at high luminosity relative to low luminosity, and the more luminous ellipticals become progressively less dense and have lower surface brightnesses than lower luminosity ellipticals. These variations can be understood as arising from differing formation histories, with more luminous galaxies having less dissipation. Data from the literature and our reanalysis of BCGs show that BCGs have radius-luminosity and Faber-Jackson relations steeper than the brightest non-BCG ellipticals in our sample, consistent with significant growth of BCGs via dissipationless mergers. The variations in slope we find in the Faber-Jackson relation of non-BCGs are qualitatively similar to that reported in the black hole mass-velocity dispersion (M_BH-sigma) correlation. This similarity is consistent with a roughly constant value of M_BH/M_star over a wide range of early type galaxies, where M_star is the stellar mass.Comment: v2: expanded analysis of BCGs; 17 pages, 9 figures; accepted in MNRA

Cascade metathesis reactions for the synthesis of taxane and isotaxane derivatives

Tricyclic isotaxane and taxane derivatives and have been synthesized by a very efficient cascade ring-closing dienyne metathesis (RCDEYM) reaction, which formed the A and B rings in one operation. When the alkyne is present at C13 (with no neighboring gem-dimethyl group), the RCEDYM reaction leads to 14,15-isotaxanes 16a,b and 18b with the gem-dimethyl group on the A ring. If the alkyne is at the C11 position (and thus flanked by a gem-dimethyl group), RCEDYM reaction only proceeds in the presence of a trisubstituted olefin at C13, which disfavors the competing diene ring-closing metathesis reaction, to give the tricyclic core of Taxol 44

Mobile Phone Communication Innovation in Multiple Time and Space Zones: The Case of Hong Kong Culture

Hong Kong is probably one of the very few places in the world where it is generally acceptable to answer incoming mobile phone calls in public places or even in the middle of a business or social meeting. In many other parts of the world, this kind of behaviour would be considered impolite or even rude because it interrupts conversations or activities. There has been considerable research carried out on mobile phones and interruption, as well as mobile phones and culture. However, there is little evidence of research on the impact of culture on the specific notion of interruption caused by mobile phones. To fill this knowledge gap, this paper presents an ethnographic study about how the Hong Kong cultural features of fast pace, deal-making and sense of urgency result in a positive perception towards mobile phone interruption. The findings indicate that Hong Kong people have innovative mobile phone communication strategies, characteristically juggling multiple identities in their stressful work pace, virtually racing with time. Comparison with other contexts is made

Synthesis of Model BC Bicycles of Taxol Using C10-C11 Ring-Closing Metathesis Strategy

6 pagesInternational audienceModel BC ring-systems of taxol 23b and 28b, which lack an oxygenated substituent at C7, have been efficiently synthesized. The key step is a ring-closing metathesis (RCM) to form the 8-membered B ring between C10 and C11. Comparison of the metathesis reaction in this route with the RCM used in a previous study with similar substrates is highlighted