Evidence for higher order QED in e+ e- pair production at RHIC

A new lowest order QED calculation for RHIC e+ e- pair production has been carried out with a phenomenological treatment of the Coulomb dissociation of the heavy ion nuclei observed in the STAR ZDC triggers. The lowest order QED result for the experimental acceptance is nearly two standard deviations larger than the STAR data. A corresponding higher order QED calculation is consistent with the data.Comment: 4 pages, 4 figures, latex, revte

Inclusive and exclusive diffractive production of dilepton pairs in proton-proton collisions at high energies

We calculate for the first time cross sections for single and central diffractive as well as exclusive diffractive production of dilepton pairs in proton-proton collisions. Several differential distributions are shown. The inclusive diffractive processes are calculated using diffractive parton distributions extracted from the analysis of diffractive structure function and dijet production at HERA. We find that the inclusive single-diffractive Drell-Yan process is by about 2 orders of magnitude smaller than ordinary Drell-Yan process. The central-diffractive processes are smaller by one order of magnitude compared to single-diffractive ones. We consider also exclusive production of dilepton pairs. The exclusive photon-pomeron (pomeron-photon) process constitutes a background to the QED photon-photon process proposed to be used for controlling luminosity at LHC. Both processes are compared then in several differential distributions. We find a region of the phase space where the photon-pomeron or pomeron-photon contributions can be larger than the photon-photon one.Comment: 20 page, 19 figure

Modelling of Quench Limit for Steady State Heat Deposits in LHC Magnets

A quench, the transition of a conductor from the superconducting to the normal conducting state, occurs irreversibly in the accelerator magnets if one of the three parameters: temperature, magnetic field or current density exceeds a critical value. Energy deposited in the superconductor by the particle beams provokes quenches detrimental for the accelerator operation. In particular if particles impacting on the vacuum chamber and their secondary showers depose energy in the magnet coils. The Large Hadron Collider (LHC) nominal beam intensity is 3.2 ldr 10^14 protons. A quench occurs if a fraction of the order of 10^7 protons per second is lost locally. A network model is used to simulate the thermodynamic behaviour of the magnets. The heat flow in the network model was validated with measurements performed in the CERN magnet test facility. A steady state heat flow was introduced in the coil by using the quench heaters implemented in the LHC magnets. The value of the heat source current is determined by the network model and the magnet coil current which is required to quench the coil is predicted accordantly. The measured and predicted value comparison is regarded as a sensitive test of the method

Preconception and prenatal testing of biologic fathers for carrier status

The familial nature of genetic conditions often requires the testing of parents and other family members in order to determine the relationship of a genetic change to a clinical phenotype or to determine potential reproductive risks. When required as part of prenatal and preconceptional genetic testing services, time constraints and the costs and risks of alternatives to testing parents require that payers have established policies for how both maternal and paternal tests that inform fetal testing choices or the interpretation of fetal testing results will be covered

Salmonella contamination of pig farm environment, Poland, 2014

Although pork is considered an important source of Salmonella infections, the introduction of control programs in pig farms are not obligatory in the EU. To resolve current epidemiological situation, monitoring of pig farms was introduced in Poland in 2014. The paper reports the first year outputs of the survey

A framework for experimental determination of localised vertical pedestrian forces on full-scale structures using wireless attitude and heading reference systems

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.A major weakness among loading models for pedestrians walking on flexible structures proposed in recent years is the various uncorroborated assumptions made in their development. This applies to spatio- temporal characteristics of pedestrian loading and the nature of multi-object interactions. To alleviate this problem, a framework for the determination of localised pedestrian forces on full-scale structures is presented using a wireless attitude and heading reference systems (AHRS). An AHRS comprises a triad of tri-axial accelerometers, gyroscopes and magnetometers managed by a dedicated data processing unit, allowing motion in three-dimensional space to be reconstructed. A pedestrian loading model based on a single point inertial measurement from an AHRS is derived and shown to perform well against benchmark data collected on an instrumented treadmill. Unlike other models, the current model does not take any predefined form nor does it require any extrapolations as to the timing and amplitude of pedestrian loading. In order to assess correctly the influence of the moving pedestrian on behaviour of a structure, an algorithm for tracking the point of application of pedestrian force is developed based on data from a single AHRS attached to a foot. A set of controlled walking tests with a single pedestrian is conducted on a real footbridge for validation purposes. A remarkably good match between the measured and simulated bridge response is found, indeed confirming applicability of the proposed framework.The research presented here was funded by EPSRC (grant EP/I029567/2). Authors thank Devon County Council for permitting the experimental campaign to be conducted on Baker Bridge in Exeter, UK, and Dr Erfan Shahabpour (supported by EPSRC grant EP/K03877X/1) for providing access to and assisting with measurements on the ADAL-3D treadmill at the University of Sheffield (funded by EPSRC grant EP/E018734/1)

Real-life measurement of tri-axial walking ground reaction forces using optimal network of wearable inertial measurement units

Monitoring natural human gait in real-life environment is essential in many applications including quantification of disease progression, and monitoring the effects of treatment and alteration of performance biomarkers in professional sports. Nevertheless, reliable and practical techniques and technologies necessary for continuous real-life monitoring of gait is still not available. This paper explores in detail the correlations between the acceleration of different body segments and walking ground reaction forces GRF( t )in three dimensions and proposes three sensory systems, with one, two and three inertial measurement units (IMUs), to estimate GRF( t )in the vertical (V), medial-lateral (ML) and anterior-posterior (AP) directions. The NARMAX non-linear system identification method was utilized to identify the optimal location for IMUs on the body for each system. A simple linear model was then proposed to estimate GRF( t )based on the correlation of segmental accelerations with each other. It was found that, for the three-IMU system, the proposed model estimatedGRF( t )with average peak-to-peak normalized root mean square error (NRMSE) of 7%, 16% and 18% in V, AP and ML directions, respectively. With a simple subject-specific training at the beginning, these errors were reduced to 7%, 13% and 13% in V, AP and ML directions, respectively. These results were found favorably comparable with the results of the benchmark NARMAX model, with subject-specific training, with 0% (V), 4% (AP) and 1% (ML) NRMSE difference

Exclusive diffractive photoproduction of dileptons by timelike Compton scattering

We derive the forward photoproduction amplitude for the diffractive $\gamma p \to l^+ l^- p$ reaction in the momentum space. within the formalism of $k_\perp$- factorization. Predictions for the $\gamma p \to l^+ l^- p$ reaction are given using unintegrated gluon distribution from the literature. We calculate the total cross section as a function of photon-proton center of mass energy and the invariant mass distribution of the lepton pair. We also discuss whether the production of timelike virtual photons can be approximated by continuing to the spacelike domain $q^2 < 0$. The present calculation provides an input for future predictions for exclusive hadroproduction in the $p p \to p l^+ l^- p$ reaction.Comment: 11 pages, 7 figure