32,950 research outputs found
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
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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 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, 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
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 -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
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