[en] The biodegradation of ring-¹⁴C- and methyl-¹⁴C-labeled paraquat by the soil yeast Lipomyces starkeyi was studied in vitro. It was found that the degradation of paraquat (acting as a sole source of culture nitrogen) resulted in the accumulation in the extracellular medium of radiolabeled acetic acid. The culture also evolved radiolabeled CO₂. The results suggest that the degradation of paraquat by L. starkeyi is associated with the integrity of the cell wall and that disruption or removal of the wall results in a complete loss of degradative capability. A mechanism for the degradation of paraquat by this organism is postulated

[en] Full text: The ATLAS detector will observe proton collisions in the Large Hadron Collider (LHC) at CERN, which is scheduled for commissioning in 2007. When operational the LHC will collide protons at a centre-of-mass energy of 14 TeV with nominally 2 X 10⁸ collisions per second at each of four beam-crossing points. ATLAS has been optimised for the detection of the hypothesised Higgs Boson, the only missing component of the otherwise experimentally well-verified electro-weak theory. In addition ATLAS is also sensitive to many other physics processes including QCD, b-physics, heavy ion interactions and those that could provide first evidence for super-symmetry. The current status of the LHC and the various aspects of the ATLAS detector will be discussed as well as the ability of ATLAS to observe new physics. The Australian contributions to the ATLAS project will also be described. These include: 1. Development and implementation of components of the Semi-Conductor Tracker (SCT), which provides spatial information for charged particles traversing the ATLAS inner detector. 2. Fast algorithms for simulating electromagnetic events in the calorimeter. 3. Development and application of fast reconstruction algorithms within the ATLAS software framework. 4. Analysis of Monte-Carlo data produced using simulated models of the ATLAS detector. The information provided will determine the most efficient strategies in searching for new physics once collisions at the LHC commence. 5. Advances in grid computing to handle the storage, transfer and offline processing of data amassed by LHC experiments, which totals over 2.4 P-bytes per annum. Copyright (2005) Australian Institute of Physics

[en] Analyses of uranium and thorium isotopes in calcite samples from thick flowstones within a high level relict cave remnant (Elder Bush Cave) indicated that the formations were beyond the range of the uranium-thorium dating technique (350 ka). ²³⁴U/²³⁸U isotope activity ratios approached unity, suggesting that the flowstones may have formed a considerable time before 350 ka. Palaeomagnetic samples taken from cores drilled through the flowstones showed the presence of both normally and reversely magnetized calcite. In some cases reversely magnetized layers overlie normally magnetized layers. This evidence, taken in conjunction with the uranium isotope data, is interpreted as indicating an Olduvai age (1.66-1.87 Ma) for some of the flowstone horizons. It is suggested that the cave became vadose by or soon after 2.0 MA. The position of the cave near the valley rim enables an estimate to be made of the maximum rate at which the present valley has been excavated. This is calculated to be 5.5 cm/ka. Remnants of old valley floors preserved within the existing valley suggest that downcutting has been a continuous process. Flowstone from a cave on one of the lower valley floor remnants (Darfur Ridge Cave) has been dated to 284 +34/-27ka allowing a maximum downcutting rate since that time of 11.2 cm/ka. The proximity of Elder Bush Cave to the valley crest suggests that its abandonment marked the onset of the incision of the present system of dales that characterize the English Peak District, presumably initiated by epeirogenic uplift or tilting. (Author)

[en] This article presents a novel design for a superconducting rf electron injector that incorporates energy recovery. This concept relaxes the demands of high power input couplers, improves essential beam parameters and energy efficiency and reduces the overall cost of a compact energy recovery linac machine.

[en] Protein G is a member of a class of cell surface bacterial proteins from Streptococcus that bind IgG with high affinity. A fragment of molecular mass 6,988, which retains IgG-binding activity, has been generated by proteolytic digestion and analyzed by ¹H NMR. Two-dimenstional DQF-COSY, TOCSY, and NOESY spectra have been employed to assign the ¹H NMR spectrum of the peptide. Elements of regular secondary structure have been identified by using nuclear Overhauser enhancement, coupling constant, and amide proton exchange data. The secondary structure consists of a central α-helix (Ala28-Val44), flanked by two portions of β-sheet (Val5-Val26 and Asp45-Lys62). This is a fundamentally different arrangement of secondary structure from that of protein A, which is made up of three consecutive α-helics in free solution. The authors conclude that the molecular mechanisms underlying the association of protein A and protein G with IgG are different

[en] The ATLAS SemiConductor Tracker (SCT) is a silicon-strip tracking detector which forms part of the ATLAS inner detector. The SCT is designed to track charged particles produced in proton-proton collisions at the Large Hadron Collider (LHC) at CERN at an energy of 14 TeV. The tracker is made up of a central barrel and two identical end-caps. The barrel contains 2112 silicon modules, while each end-cap contains 988 modules. The overall tracking performance depends not only on the intrinsic measurement precision of the modules but also on the characteristics of the whole assembly, in particular, the stability and the total material budget. This paper describes the engineering design and construction of the SCT end-caps, which are required to support mechanically the silicon modules, supply services to them and provide a suitable environment within the inner detector. Critical engineering choices are highlighted and innovative solutions are presented - these will be of interest to other builders of large-scale tracking detectors. The SCT end-caps will be fully connected at the start of 2008. Further commissioning will continue, to be ready for proton-proton collision data in 2008

[en] The ATLAS SemiConductor Tracker (SCT) was built in three sections: a barrel and two end-caps. This paper describes the design, construction and final integration of the barrel section. The barrel is constructed around four nested cylinders that provide a stable and accurate support structure for the 2112 silicon modules and their associated services. The emphasis of this paper is directed at the aspects of engineering design that turned a concept into a fully-functioning detector, as well as the integration and testing of large sub-sections of the final SCT barrel detector. The paper follows the chronology of the construction. The main steps of the assembly are described with the results of intermediate tests. The barrel service components were developed and fabricated in parallel so that a flow of detector modules, cooling loops, opto-harnesses and Frequency-Scanning-Interferometry (FSI) alignment structures could be assembled onto the four cylinders. Once finished, each cylinder was conveyed to the next site for the mounting of modules to form a complete single barrel. Extensive electrical and thermal function tests were carried out on the completed single barrels. In the next stage, the four single barrels and thermal enclosures were combined into the complete SCT barrel detector so that it could be integrated with the Transition Radiation Tracker (TRT) barrel to form the central part of the ATLAS inner detector. Finally, the completed SCT barrel was tested together with the TRT barrel in noise tests and using cosmic rays.

[en] In 2004 at the ATLAS (A Toroidal LHC ApparatuS) combined test beam, one slice of the ATLAS barrel detector (including an Inner Detector set-up and the Liquid Argon calorimeter) was exposed to particles from the H8 SPS beam line at CERN. It was the first occasion to test the combined electron performance of ATLAS. This paper presents results obtained for the momentum measurement p with the Inner Detector and for the performance of the electron measurement with the LAr calorimeter (energy E linearity and resolution) in the presence of a magnetic field in the Inner Detector for momenta ranging from 20 GeV/c to 100 GeV/c. Furthermore the particle identification capabilities of the Transition Radiation Tracker, Bremsstrahlungs-recovery algorithms relying on the LAr calorimeter and results obtained for the E/p ratio and a way how to extract scale parameters will be discussed.

[en] The reconstruction of photons in the ATLAS detector is studied with data taken during the 2004 Combined Test Beam, where a full slice of the ATLAS detector was exposed to beams of particles of known energy at the CERN SPS. The results presented show significant differences in the longitudinal development of the electromagnetic shower between converted and unconverted photons as well as in the total measured energy. The potential to use the reconstructed converted photons as a means to precisely map the material of the tracker in front of the electromagnetic calorimeter is also considered. All results obtained are compared with a detailed Monte-Carlo simulation of the test-beam setup which is based on the same simulation and reconstruction tools as those used for the ATLAS detector itself.

[en] A new method for calibrating the hadron response of a segmented calorimeter is developed and successfully applied to beam test data. It is based on a principal component analysis of energy deposits in the calorimeter layers, exploiting longitudinal shower development information to improve the measured energy resolution. Corrections for invisible hadronic energy and energy lost in dead material in front of and between the calorimeters of the ATLAS experiment were calculated with simulated Geant4 Monte Carlo events and used to reconstruct the energy of pions impinging on the calorimeters during the 2004 Barrel Combined Beam Test at the CERN H8 area. For pion beams with energies between 20GeV and 180GeV, the particle energy is reconstructed within 3% and the energy resolution is improved by between 11% and 25% compared to the resolution at the electromagnetic scale.