A study of Double Pomeron Exchange in ALICE

The non-Abelian nature of QCD suggests that particles that have a gluon constituent, such as glueballs or hybrids, should exist. Experiments WA76, WA91 and WA102 have performed a dedicated search for these states in central production using the CERN Omega Spectrometer. New results from central production show that there is a kinematical filter which can select out glueball candidates from known qqbar states. A further study of this at high energies is essential in order to get information on the M(X0) > 2 GeV region. This paper describes how this could be done using the the ALICE detector at the LHC.Comment: 17 pages, Latex, 7 Figure

Automated real time detection of solar wind shocks and consequences for the identification of SSC and SI events

Algorithms have been developed to automatically detect Earth bound shocks in the solar wind as measured by the ACE satellite. These involve simple threshold techniques and wavelet analysis. One practical application of this shock detection is that it can provide power companies with advanced warning of the potential for geomagnetically induced currents. The automatically detected shocks have been tested against published lists of known shocks and accuracy statistics are presented. Another use for automated shock detection is an aid to the preparation of lists of rapid variations: SSC and SI events. To contribute to the IAGA published list of rapid variations, as prepared by Ebro Observatory, BGS staff routinely identify, scale and classify the events recorded at the three UK magnetic observatories. This is carried out using the criteria from the Atlas of Rapid Variations (1959) and subsequent IAGA instructions. The usefulness of automated detection of solar wind shocks for this task is examined by testing these against lists of identified SSC and SI events

Space weather effects on drilling accuracy in the North Sea

The oil industry uses geomagnetic field information to aid directional drilling operations when drilling for oil and gas offshore. These operations involve continuous monitoring of the azimuth and inclination of the well path to ensure the target is reached and, for safety reasons, to avoid collisions with existing wells. Although the most accurate method of achieving this is through a gyroscopic survey, this can be time consuming and expensive. An alternative method is a magnetic survey, where measurements while drilling (MWD) are made along the well by magnetometers housed in a tool within the drill string. These MWD magnetic surveys require estimates of the Earth’s magnetic field at the drilling location to correct the downhole magnetometer readings. The most accurate corrections are obtained if all sources of the Earth’s magnetic field are considered. Estimates of the main field generated in the core and the local crustal field can be obtained using mathematical models derived from suitable data sets. In order to quantify the external field, an analysis of UK observatory data from 1983 to 2004 has been carried out. By accounting for the external field, the directional error associated with estimated field values at a mid-latitude oil well (55 N) in the North Sea is shown to be reduced by the order of 20%. This improvement varies with latitude, local time, season and phase of the geomagnetic activity cycle. By accounting for all sources of the field, using a technique called Interpolation In-Field Referencing (IIFR), directional drillers have access to data from a “virtual” magnetic observatory at the drill site. This leads to an error reduction in positional accuracy that is close to matching that of the gyroscopic survey method and provides a valuable independent technique for quality control purposes

An Effective Model for Crumpling in Two Dimensions?

We investigate the crumpling transition for a dynamically triangulated random surface embedded in two dimensions using an effective model in which the disordering effect of the $X$ variables on the correlations of the normals is replaced by a long-range ``antiferromagnetic'' term. We compare the results from a Monte Carlo simulation with those obtained for the standard action which retains the $X$'s and discuss the nature of the phase transition.Comment: 5 page

A Prototype Fast Multiplicity Discriminator for ALICE L0 Trigger

The design details and test results of a prototype Multiplicity Discriminator (MD) for the ALICE L0 Trigger electronics are presented. The MD design is aimed at the earliest trigger decision founded on a fast multiplicity signal cut, in both options for the ALICE centrality detector: Micro Channel Plates or Cherenkov counters. The MD accepts detector signals with an amplitude range of plus-minus 2.5 V, base duration of 1.8 ns and rise time of 300-400 ps. The digitally controlled threshold settings give an accuracy better than 0.4% at the maximum amplitude of the accepted pulses. The MD internal latency of 15 ns allows for a decision every LHC bunch crossing period, even for the 40 MHz of p-p collisions

Project EURISGIC : worst case scenarios (technical note D5.1)

The overall objective of Work Package 5 of the EURISGIC project (see website eurisgic.eu) is defined as being: “Estimate the largest possible GIC flowing anywhere in the European high-voltage power grid, based on archive data.” This document is a technical note (deliverable item D5.1) for the results of this work package. For each of the project team members participating in the work package (FMI – Finland; Neurospace – Sweden; IRF – Sweden; NASA and Catholic University of America - USA; BGS - UK) we summarise activities related to worst case scenario modelling: activities such as research into extreme event statistical methods, theoretical extreme event modelling and individual (historical and hypothetical) event studies. We note that research is continuing and therefore some results reported here are subject to further confirmation in published scientific journals

Grand-Canonical Ensemble of Random Surfaces with Four Species of Ising Spins

The grand-canonical ensemble of dynamically triangulated surfaces coupled to four species of Ising spins (c=2) is simulated on a computer. The effective string susceptibility exponent for lattices with up to 1000 vertices is found to be $\gamma = - 0.195(58)$. A specific scenario for $c > 1$ models is conjectured.Comment: LaTeX, 11 pages + 1 postscript figure appended, preprint LPTHE-Orsay 94/1

Subtractive CRISPR screen identifies the ATG16L1/vacuolar ATPase axis as required for non-canonical LC3 lipidation

Although commonly associated with autophagosomes, LC3 can also be recruited to membranes by covalent lipidation in a variety of non-canonical contexts. These include responses to ionophores such as the M2 proton channel of influenza A virus. We report a subtractive CRISPR screen that identifies factors required for non-canonical LC3 lipidation. As well as the enzyme complexes directly responsible for LC3 lipidation in all contexts, we show the RALGAP complex is important for M2-induced, but not ionophore drug-induced, LC3 lipidation. In contrast, ATG4D is responsible for LC3 recycling in M2-induced and basal LC3 lipidation. Identification of a vacuolar ATPase subunit in the screen suggests a common mechanism for non-canonical LC3 recruitment. Influenza-induced and ionophore drug-induced LC3 lipidation lead to association of the vacuolar ATPase and ATG16L1 and can be antagonized by Salmonella SopF. LC3 recruitment to erroneously neutral compartments may therefore represent a response to damage caused by diverse invasive pathogens