Measurement of event-shape observables in Z→ℓ+ℓ− events in pp collisions at √ s=7 TeV with the ATLAS detector at the LHC

Event-shape observables measured using charged particles in inclusive $Z$-boson events are presented, using the electron and muon decay modes of the $Z$ bosons. The measurements are based on an integrated luminosity of $1.1 {\rm fb}^{-1}$ of proton--proton collisions recorded by the ATLAS detector at the LHC at a centre-of-mass energy $\sqrt{s}=7$ TeV. Charged-particle distributions, excluding the lepton--antilepton pair from the $Z$-boson decay, are measured in different ranges of transverse momentum of the $Z$ boson. Distributions include multiplicity, scalar sum of transverse momenta, beam thrust, transverse thrust, spherocity, and $\mathcal{F}$-parameter, which are in particular sensitive to properties of the underlying event at small values of the $Z$-boson transverse momentum. The Sherpa event generator shows larger deviations from the measured observables than Pythia8 and Herwig7. Typically, all three Monte Carlo generators provide predictions that are in better agreement with the data at high $Z$-boson transverse momenta than at low $Z$-boson transverse momenta and for the observables that are less sensitive to the number of charged particles in the event.Comment: 36 pages plus author list + cover page (54 pages total), 14 figures, 4 tables, submitted to EPJC, All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2014-0

Why polar gigantism and palaeozoic gigantism are not equivalent: Effects of oxygen and temperature on the body size of ectotherms

Contains fulltext : 123399.pdf (publisher's version ) (Open Access

Occurrence of aquatic invertebrates of the wheatbelt region of Western Australia in relation to salinity

The wheatbelt region of Western Australia has been extensively cleared of indigenous vegetation for agriculture and is now severely affected by dryland salinity. Wetlands that were once freshwater are now saline and others are under threat, as are the animals and plants that inhabit them. Rising groundwater is also affecting the many naturally saline playas. To provide a framework for setting conservation priorities in this region a biological survey was undertaken, including sampling of aquatic invertebrates at 230 wetlands. In this paper, we have used data from the survey to summarise occurrence of species in relation to salinity. Total species richness at a wetland showed no response to salinity below 4.1 g l)1 and then declined dramatically as salinity increased. When halophilic species were excluded from consideration, species richness was found to decline from 2.6 g l)1. These patterns are compared to previous studies of richnesssalinity relationships. There is some evidence that the freshwater invertebrate fauna of the wheatbelt may be comparatively salt tolerant, with 46% of freshwater species collected at salinities above 3 g l)1 and 17% above 10 g l)1, though these proportions differed between various invertebrate groups. While this tolerance will provide a buffer against the effects of mild salinisation, many species are at risk of regional extinction as salinisation becomes more widespread.Adrian M. Pinder, Stuart A. Halse, Jane M. McRae & Russell J. Shie