Trigger and data acquisition

The lectures address some of the issues of triggering and data acquisition in large high-energy physics experiments. Emphasis is placed on hadron-collider experiments that present a particularly challenging environment for event selection and data collection. However, the lectures also explain how T/DAQ systems have evolved over the years to meet new challenges. Some examples are given from early experience with LHC T/DAQ systems during the 2008 single-beam operations.Comment: 32 pages, Lectures given at the 5th CERN-Latin-American School of High-Energy Physics, Recinto Quirama, Colombia, 15 - 28 Mar 200

Sickle cell anaemia and the experiences of young people living with the condition

This qualitative literature review examines the experiences of young people with Sickle Cell Anaemia (SCA). Sickle cell anaemia (SCA) is a condition acknowledged for its unpredictability, painful episodes and life threatening nature. The aim was to explore the impact SCA has on young people and the experiences they face. After reviewing potential articles found from the EBSCOhost platform, an inclusion and exclusion criteria was used and six appropriate studies were found with the majority of the participants in the 10-25 age range. However, one study had some participants in the early childhood and another had some of the sample in the young adult age range. These articles concentrated on the UK and North America instead of a broader international experience. The critical appraisal skills programme (CASP) was then used to evaluate the articles found. Thematic analysis identified three themes: acceptance, support and unpredictability, with subthemes of spirituality and discrimination. It was clear that SCA affected multiple areas of young peoples’ lives, and health professionals need to consider young people’s views. The terms Sickle Cell Anaemia and Sickle Cell Disease are used interchangeably throughout this review

High-Energy QCD as a Topological Field Theory

We propose an identification of the conformal field theory underlying Lipatov's spin-chain model of high-energy scattering in perturbative QCD. It is a twisted N=2 supersymmetric topological field theory, which arises as the limiting case of the SL(2,R)/U(1) non-linear sigma model that also plays a role in describing the Quantum Hall effect and black holes in string theory. The doubly-infinite set of non-trivial integrals of motion of the high-energy spin-chain model displayed by Faddeev and Korchemsky are identified as the Cartan subalgebra of a W_{\infty} \otimes W_{\infty} bosonic sub-symmetry possessed by this topological theory. The renormalization group and an analysis of instanton perturbations yield some understanding why this particular topological spin-chain model emerges in the high-energy limit, and provide a new estimate of the asymptotic behaviour of multi-Reggeized-gluon exchange.Comment: 24 pages LATEX, one eps figure incorporate

Could a nearby supernova explosion have caused a mass extinction?

We examine the possibility that a nearby supernova explosion could have caused one or more of the mass extinctions identified by palaeontologists. We discuss the likely rate of such events in the light of the recent identification of Geminga as a supernova remnant less than 100 pc away and the discovery of a millisecond pulsar about 150 pc away, and observations of SN 1987A. The fluxes of $\gamma$ radiation and charged cosmic rays on the Earth are estimated, and their effects on the Earth's ozone layer discussed. A supernova explosion of the order of 10 pc away could be expected every few hundred million years, and could destroy the ozone layer for hundreds of years, letting in potentially lethal solar ultraviolet radiation. In addition to effects on land ecology, this could entail mass destruction of plankton and reef communities, with disastrous consequences for marine life as well. A supernova extinction should be distinguishable from a meteorite impact such as the one that presumably killed the dinosaurs.Comment: 10 pages, CERN-TH.6805/9

Some Physical Aspects of Liouville String Dynamics

We discuss some physical aspects of our Liouville approach to non-critical strings, including the emergence of a microscopic arrow of time, effective field theories as classical ``pointer'' states in theory space, $CPT$ violation and the possible apparent non-conservation of angular momentum. We also review the application of a phenomenological parametrization of this formalism to the neutral kaon system.Comment: CERN-TH.7269/94, 37 pages, 2 figures (not included), latex. Direct inquiries to: [email protected]

A Liouville String Approach to Microscopic Time and Cosmology

In the non-critical string framework that we have proposed recently, the time $t$ is identified with a dynamical local renormalization group scale, the Liouville mode, and behaves as a statistical evolution parameter, flowing irreversibly from an infrared fixed point - which we conjecture to be a topological string phase - to an ultraviolet one - which corresponds to a static critical string vacuum. When applied to a toy two-dimensional model of space-time singularities, this formalism yields an apparent renormalization of the velocity of light, and a $t$-dependent form of the uncertainty relation for position and momentum of a test string. We speculate within this framework on a stringy alternative to conventional field-theoretical inflation, and the decay towards zero of the cosmological constant in a maximally-symmetric space.Comment: Latex 23 pages, no figures, CERN-TH.7000/93, CTP-TAMU-66/9

High-temperature constitutive modeling

Thermomechanical service conditions for high-temperature levels, thermal transients, and mechanical loads severe enough to cause measurable inelastic deformation are studied. Structural analysis in support of the design of high-temperature components depends strongly on accurate mathematical representations of the nonlinear, hereditary, inelastic behavior of structural alloys at high temperature, particularly in the relatively small strain range. Progress is discussed in the following areas: multiaxial experimentation to provide a basis for high-temperature multiaxial constitutive relationships; nonisothermal testing and theoretical development toward a complete thermomechanically path dependent formulation of viscoplasticity; and development of viscoplastic constitutive model accounting for initial anisotropy