1,336 research outputs found
Calculated collision induced absorption spectrum for He-Ar
Calculation of collision induced absorption spectra for helium-argo
The StoreGate: a Data Model for the Atlas Software Architecture
The Atlas collaboration at CERN has adopted the Gaudi software architecture
which belongs to the blackboard family: data objects produced by knowledge
sources (e.g. reconstruction modules) are posted to a common in-memory data
base from where other modules can access them and produce new data objects. The
StoreGate has been designed, based on the Atlas requirements and the experience
of other HENP systems such as Babar, CDF, CLEO, D0 and LHCB, to identify in a
simple and efficient fashion (collections of) data objects based on their type
and/or the modules which posted them to the Transient Data Store (the
blackboard). The developer also has the freedom to use her preferred key class
to uniquely identify a data object according to any other criterion. Besides
this core functionality, the StoreGate provides the developers with a powerful
interface to handle in a coherent fashion persistable references, object
lifetimes, memory management and access control policy for the data objects in
the Store. It also provides a Handle/Proxy mechanism to define and hide the
cache fault mechanism: upon request, a missing Data Object can be transparently
created and added to the Transient Store presumably retrieving it from a
persistent data-base, or even reconstructing it on demand.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, Ca, USA, March 2003, 4 pages, LaTeX, MOJT00
First-principles kinetic Monte Carlo simulations for heterogeneous catalysis, applied to the CO oxidation at RuO2(110)
We describe a first-principles statistical mechanics approach enabling us to
simulate the steady-state situation of heterogeneous catalysis. In a first step
density-functional theory together with transition-state theory is employed to
obtain the energetics of all relevant elementary processes. Subsequently the
statistical mechanics problem is solved by the kinetic Monte Carlo method,
which fully accounts for the correlations, fluctuations, and spatial
distributions of the chemicals at the surface of the catalyst under
steady-state conditions. Applying this approach to the catalytic oxidation of
CO at RuO2(110), we determine the surface atomic structure and composition in
reactive environments ranging from ultra-high vacuum (UHV) to technologically
relevant conditions, i.e. up to pressures of several atmospheres and elevated
temperatures. We also compute the CO2 formation rates (turnover frequencies).
The results are in quantitative agreement with all existing experimental data.
We find that the high catalytic activity of this system is intimately connected
with a disordered, dynamic surface ``phase'' with significant compositional
fluctuations. In this active state the catalytic function results from a
self-regulating interplay of several elementary processes.Comment: 18 pages including 9 figures; related publications can be found at
http://www.fhi-berlin.mpg.de/th/th.htm
Kinetic Characterisation of a Single Chain Antibody against the Hormone Abscisic Acid: Comparison with Its Parental Monoclonal
A single-chain Fv fragment antibody (scFv) specific for the plant hormone abscisic acid (ABA) has been expressed in the bacterium Escherichia coli as a fusion protein. The kinetics of ABA binding have been measured using surface plasmon resonance spectrometry (BIAcore 2000) using surface and solution assays. Care was taken to calculate the concentration of active protein in each sample using initial rate measurements under conditions of partial mass transport limitation. The fusion product, parental monoclonal antibody and the free scFv all have low nanomolar affinity constants, but there is a lower dissociation rate constant for the parental monoclonal resulting in a three-fold greater affinity. Analogue specificity was tested and structure-activity binding preferences measured. The biologically-active (+)-ABA enantiomer is recognised with an affinity three orders of magnitude higher than the inactive (-)-ABA. Metabolites of ABA including phaseic acid, dihydrophaseic acid and deoxy-ABA have affinities over 100-fold lower than that for (+)-ABA. These properties of the scFv make it suitable as a sensor domain in bioreporters specific for the naturally occurring form of ABA
Alloy surface segregation in reactive environments: A first-principles atomistic thermodynamics study of Ag3Pd(111) in oxygen atmospheres
We present a first-principles atomistic thermodynamics framework to describe
the structure, composition and segregation profile of an alloy surface in
contact with a (reactive) environment. The method is illustrated with the
application to a Ag3Pd(111) surface in an oxygen atmosphere, and we analyze
trends in segregation, adsorption and surface free energies. We observe a wide
range of oxygen adsorption energies on the various alloy surface
configurations, including binding that is stronger than on a Pd(111) surface
and weaker than that on a Ag(111) surface. This and the consideration of even
small amounts of non-stoichiometries in the ordered bulk alloy are found to be
crucial to accurately model the Pd surface segregation occurring in
increasingly O-rich gas phases.Comment: 13 pages including 6 figures; related publications can be found at
http://www.fhi-berlin.mpg.de/th/th.htm
Report of the AOD Format Task Force
The Analysis Object Data (AOD) are produced by ATLAS reconstruction and are the main input for most analyses. AOD, like the Event Summary Data (ESD, the other main output of reconstruction) are written as POOL files and are readable from Athena, and, to a limited extent, from ROOT. The AOD typical size, processing speed, and their relatively complex class structure and package dependencies, make them inconvenient to use for most interactive analysis. According to the computing model, interactive analysis will be based on Derived Physics Data (DPD), a user-defined format commonly produced from the AOD. As of release 12.0.3 it is common practice to write DPD as Athena-aware Ntuples (AANT) in ROOT. In an effort to organize and standardize AANT, we introduced the Structured Athena-aware Ntuple (SAN), an AANT containing objects that behave, as much as it is allowed by ROOT interpreter limitations, as their AOD counterparts. Recently it was proposed to extend SAN functionality beyond DPD implementation. SAN objects would be used as AOD objects. The TOB formed our task force with the mandate to "perform a technical evaluation of the two proposals, one based upon the existing AOD classes and architecture, the other upon Structured Athena-Aware Ntuples. [...] Criteria for the evaluation should include I/O performance, support for schema evolution, suitability for end user analysis and simplicity.
The T2K Side Muon Range Detector
The T2K experiment is a long baseline neutrino oscillation experiment aiming
to observe the appearance of {\nu} e in a {\nu}{\mu} beam. The {\nu}{\mu} beam
is produced at the Japan Proton Accelerator Research Complex (J-PARC), observed
with the 295 km distant Super- Kamiokande Detector and monitored by a suite of
near detectors at 280m from the proton target. The near detectors include a
magnetized off-axis detector (ND280) which measures the un-oscillated neutrino
flux and neutrino cross sections. The present paper describes the outermost
component of ND280 which is a side muon range detector (SMRD) composed of
scintillation counters with embedded wavelength shifting fibers and Multi-Pixel
Photon Counter read-out. The components, performance and response of the SMRD
are presented.Comment: 13 pages, 19 figures v2: fixed several typos; fixed reference
Routes to sustainability in public food procurement: An investigation of different models in primary school catering
Increasingly, policymakers are setting ambitious goals for sustainability in public procurement, integrated across different pillars. Such ambitions are apparent in public catering services, where procurement models have been shifting towards greater localisation of supply chains and purchasing of more organically grown food. To date however, few studies have examined empirically what the impacts of different procurement models are across these multiple pillars of sustainability. This research aimed to fill the gap, by measuring and comparing the environmental, economic and nutritional outcomes of different models of school meals procurement. Case studies were undertaken of ten primary school meals services in five European countries, capturing different procurement model types. Results showed carbon emissions ranged from 0.95 kgs CO2e per meal in the lowest case to 2.41 kgs CO2e in the highest case, with adoption of low carbon food waste disposal methods and reduction of the amount of ruminant meat in the menus being the most important actions for lowering emissions. In terms of economic impact, local economic multiplier ratios ranged from 1.59 to 2.46, and although the level of local food sourcing contributed to these ratios, the effect was eclipsed, in some cases, by investment in local catering staff. Meanwhile, implementation of a robust standards regime and improving canteen environment and supervision were the most important actions for nutritional quality and intake. The paper discusses the implications of the findings for integrated, sustainable models of food procurement
Organization and management of ATLAS offline software releases
ATLAS is one of the largest collaborations ever undertaken in the physical sciences. This paper explains how the software infrastructure is organized to manage collaborative code development by around 300 developers with varying degrees of expertise, situated in 30 different countries. ATLAS offline software currently consists of about 2 million source lines of code contained in 6800 C++ classes, organized in almost 1000 packages. We will describe how releases of the offline ATLAS software are built, validated and subsequently deployed to remote sites. Several software management tools have been used, the majority of which are not ATLAS specific; we will show how they have been integrated
Standalone vertex ďŹnding in the ATLAS muon spectrometer
A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at âs = 7 TeV collected with the ATLAS detector at the LHC during 2011
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