The evolution of galaxy groups and of galaxies therein

Properties of groups of galaxies depend sensitively on the algorithm for group selection, and even the most recent catalogs of groups built from redshift-space selection should suffer from projections and infalling galaxies. The cosmo-dynamical evolution of groups from initial Hubble expansion to collapse and virialization leads to a fundamental track (FT) in virial-theorem-M/L vs crossing time. The increased rates of mergers, both direct and after dynamical friction, in groups relative to clusters, explain the higher fraction of elliptical galaxies at given local number density in X-ray selected groups, relative to clusters, even when the hierarchical evolution of groups is considered. Galaxies falling into groups and clusters should later travel outwards to typically 2 virial radii, which is somewhat less than the outermost radius where observed galaxy star formation efficiencies are enhanced relative to field galaxies of same morphological type. An ongoing analysis of the internal kinematics of X-ray selected groups suggests that the radial profiles of line of sight velocity dispersion are consistent with isotropic NFW distributions for the total mass density, with higher (lower) concentrations than LambdaCDM predictions in groups of high (low) mass. The critical mass, at M200 ~ 10^13 M_sun is consistent with possible breaks in the X-ray luminosity-temperature and Fundamental Plane relations. The internal kinematics of groups indicate that the M-T relation of groups should agree with that extrapolated from clusters with no break at the group scale. The analyses of observed velocity dispersion profiles and of the FT both suggest that low velocity dispersion groups (compact and loose, X-ray emitting or undetected) are quite contaminated by chance projections.Comment: Invited review, ESO workshop "Groups of Galaxies in the Nearby Universe", held in Santiago, Chile, 5-9 December 2005, ed. I. Saviane, V. Ivanov & J. Borissova, 16 page

Four specimens of Pteroeides Steenstrupii Kölliker collected by P. Buitendijk, Tandjong Priok 1907

There are 4 specimens with the following measurements in length: specimen A. 280 mm. specimen C. 100 mm. „ B. 150 „ „ D. 90 „ The largest of these has fully developed leaves with a marginal length of about 40 mm. In specimen B the leaves are represented by broad triangular lobes having a maximum marginal length of 5 mm. In specimen C the leaves are also remarkably small but larger than in specimen B. In specimen D, the smallest of the series, the leaves are still larger having a maximum marginal length of 10 mm. It is evident, I think, that of these four specimens only one (specimen A) is normal. The others have either been injured or have undergone some pathological change. It is difficult to understand what kind of injury the specimens could have undergone which destroyed all the leaves and left the rachis intact unless they were attacked by some carnivorous fish that had a partiality for the leaves. It is however extremely improbable that Pteroeides is preyed upon by any carnivorous animal. I have examined a very large number of specimens of the genus from different parts of the world and have never seen any injury to the leaves that could be attributed to fish bites. The only Pennatulacean that has been found in the stomach of fish is Virgularia, a genus which has no spicules in any part of the leaves or rachis; and there is no evidence that any other genus of Pennatulacea is attacked by fish or any other carnivorous animals. Th

Successful decision making in organisations

Also known as ARI research note 96-62SIGLEAvailable from British Library Document Supply Centre-DSC:0678.231F(AD-A--313540)(microfiche) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Low carbohydrate diets and performance

Athletes are continually searching for means to optimize their performance. Within the past 20 years, athletes and scientists have reported and/or observed that consuming a carbohydrate restricted diet may improve performance. The original theories explaining the purported benefits centered on the fact that fat oxidation increases, thereby "sparing" muscle glycogen. More recent concepts that explain the plausibility of the ergogenicity of low carbohydrate, or high fat, diets on exercise performance pertain to an effect similar to altitude training. We and others have observed that, while fat oxidation may be increased, the ability to maintain high intensity exercise (e.g., above the lactate threshold) seems to be compromised or at least indifferent compared to when more carbohydrate was consumed. That said, clinical studies clearly demonstrate that ad-libitum low carbohydrate diets elicit greater decreases in body weight and fat than energy equivalent low fat diets, especially over a short duration. Thus, while low carbohydrate and high fat diets appear detrimental or indifferent relative to performance, they may be a faster means to achieve a more competitive body composition