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

Binding effects in multivalent Gibbs-Donnan equilibrium

The classical Gibbs-Donnan equilibrium describes excess osmotic pressure associated with confined colloidal charges embedded in an electrolyte solution. In this work, we extend this approach to describe the influence of multivalent ion binding on the equilibrium force acting on a charged rod translocating between two compartments, thereby mimicking ionic effects on force balance during in vitro DNA ejection from bacteriophage. The subtle interplay between Gibbs-Donnan equilibrium and adsorption equilibrium leads to a non-monotonic variation of the ejection force as multivalent salt concentration is increased, in qualitative agreement with experimental observations

Separation of suspended particles in microfluidic systems by directional-locking in periodic fields

We investigate the transport and separation of overdamped particles under the action of a uniform external force in a two-dimensional periodic energy landscape. Exact results are obtained for the deterministic transport in a square lattice of parabolic, repulsive centers that correspond to a piecewise-continuous linear-force model. The trajectories are periodic and commensurate with the obstacle lattice and exhibit phase-locking behavior in that the particle moves at the same average migration angle for a range of orientation of the external force. The migration angle as a function of the orientation of the external force has a Devil's staircase structure. The first transition in the migration angle was analyzed in terms of a Poincare map, showing that it corresponds to a tangent bifurcation. Numerical results show that the limiting behavior for impenetrable obstacles is equivalent to the high Peclet number limit in the case of transport of particles in a periodic pattern of solid obstacles. Finally, we show how separation occurs in these systems depending on the properties of the particles

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

The South African child death review pilot: A multiagency approach to strengthen healthcare and protection for children

Background. Child mortality trends in South Africa (SA) show a decrease, but remain high and appear to have plateaued. To attain the new sustainable development goals, we need a better understanding of causes of death and the associated factors.Objectives. To describe the SA child death review (CDR) pilot, the pattern of child deaths reviewed and the factors associated with these deaths.Methods. CDR teams were established at two pilot sites, Salt River mortuary (Western Cape Province) and Phoenix mortuary (KwaZulu-Natal Province). All child deaths were reviewed by a multidisciplinary team at the pilot sites for the period 1 January 2014 - 31 December 2014.Results. The CDR pilot reviewed 711 cases. Over half (53.3%) were natural deaths, as opposed to 42.6% non-natural deaths. Most infant deaths (83.9%) were due to natural causes, while 91.7% of deaths in the 15 - 17-year-old age group were due to injuries. The leading cause of deaths reviewed (30.8%) was respiratory tract infection (RTI), mainly among infants (51.6%). Homicide was the second most common cause of death and affected children of all ages, with the highest burden (52.8%) in the 15 - 17-year age group. Child abuse and neglect accounted for 11.3% of deaths. RTI was shown to be more likely after the neonatal period (odds ratio (OR) 2.92; p<0.000) and in preterm infants (OR 1.98; p=0.005).Conclusions. CDR teams have been effective in improving identification of the causes of out-of-hospital deaths, as well as by identifying remediable factors critical to reducing child deaths further

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

First Report of the Simulation Optimization Group

This is the first report of the ATLAS Simulation Optimization Group, established in June of 2007. This article justifies the selected Geant4 version, physics list, and range cuts to be used by the default ATLAS simulation for initial data taking and beyond. The current status of several projects, including detector description, simulation validation, studies of additional Geant4 parameters, and cavern background, are reported