Adaptation to Abundant Low Quality Food Improves the Ability to Compete for Limited Rich Food in Drosophila melanogaster.

The rate of food consumption is a major factor affecting success in scramble competition for a limited amount of easy-to-find food. Accordingly, several studies report positive genetic correlations between larval competitive ability and feeding rate in Drosophila; both become enhanced in populations evolving under larval crowding. Here, we report the experimental evolution of enhanced competitive ability in populations of D. melanogaster previously maintained for 84 generations at low density on an extremely poor larval food. In contrast to previous studies, greater competitive ability was not associated with the evolution of higher feeding rate; if anything, the correlation between the two traits across lines tended to be negative. Thus, enhanced competitive ability may be favored by nutritional stress even when competition is not intense, and competitive ability may be decoupled from the rate of food consumption

Response of the ATLAS Tile calorimeter prototype to muons

A study of high energy muons traversing the ATLAS hadron the calorimeter in the barrel region in the energy range between 10 and 300 GeV is presented. Both test beam experimental data and Monte Carlo simulations are given and show good agreement. The Tile calorimeter capability of detecting isolated muons over the above energy range is demonstrated. A signal to background ratio of about 10 is expected for the nominal LHC luminosity (10(34) l/cm(2) s). The photoelectron statistics effect in the muon shape response is shown. The e/mip ratio is found to be 0.81 +/- 0.03; the e/mu ratio is in the range 0.91-0.97. The energy loss of a muon in the calorimeter, dominated by the energy lost in the absorber, can be correlated to the energy loss in the active material. This correlation allows one to correct on an event by event basis the muon energy loss in the calorimeter and therefore reduce the low energy tails in the muon momentum distribution

Response of the ATLAS Tile calorimeter prototype to muons

A study of high energy muons traversing the ATLAS hadron Tile calorimeter in the barrel region in the energy range between 10 and 300 GeV is presented. Both test beam experimental data and Monte Carlo simulations are given and show good agreement. The Tile calorimeter capability of detecting isolated muons over the above energy range is demonstrated. A signal to background ratio of about 10 is expected for the nominal LHC luminosity (1034 1/cm2s). The photoelectron statistics effect in the muon shape response is shown. The e/mip ratio is found to be 0.81 ± 0.03; the e/μ ratio is in the range 0.91-0.97. The energy loss of a muon in the calorimeter, dominated by the energy lost in the absorber, can be correlated to the energy loss in the active material. This correlation allows one to correct on an event by event basis the muon energy loss in the calorimeter and therefore reduce the low energy tails in the muon momentum distribution

A measurement of the energy loss spectrum of 150 GeV muons in iron

The energy loss spectrum of 150 GeV muons has been measured with a prototype of the ATLAS hadron calorimeter in the H8 beam of the CERN SPS. The differential probability dP/d upsilon per radiation length of a fractional energy loss upsilon = Delta E(mu)E(upsilon) has been measured in the range upsilon = 0.01 divided by 0.95; it is compared with the theoretical predictions for energy losses due to bremsstrahlung and production of electron-positron pairs or of energetic knock-on electrons. The integrated probability integral(0.01)(0.95)(dP/d upsilon)d upsilon is (1.610 +/- 0.015(stat) +/- 0.105(syst)). 10(-3) in agreement with the theoretical predictions 1.556 . 10(-3) and 1.619 . 10(-3). Agreement with theory is also found in two intervals of upsilon where production of electron-positron pairs and knock-on electrons dominates. In the region of bremsstrahlung dominance (upsilon = 0.12 divided by 0.95) the measured integrated probability (1.160 +/- 0.040(stat) +/- 0.075(syst)). 10(-4) is in agreement with the theoretical value of 1.185 . 10(-4), obtained using the Petrukhin and Shestakov description of the bremsstrahlung process. The same result is about 3.6 standard deviations (defined as the quadratic sum of statistical and systematic errors) lower than the theoretical prediction of 1.472 . 10(-4) obtained using Tsai's description of bremsstrahlung

Evaluation of Fermi read-out of the Atlas Tilecal prototype

Prototypes of the FERMI system have been used to read out a prototype of the ATLAS hadron calorimeter in a beam test at the CERN SPS. The FERMI read-out system, using a compressor and a sampling ADC, is compared to a standard charge integrating read-out by measuring the energy resolution of the calorimeter separately with the two systems on the same events. Signal processing techniques have been designed to optimize the treatment of FERMI data. The resulting energy resolution is better than the one obtained with the standard read-out. (C) 1998 Elsevier Science B.V. All rights reserved