164 research outputs found
Photon - Jet Correlations and Constraints on Fragmentation Functions
We study the production of a large-pT photon in association with a jet in
proton-proton collisions. We examine the sensitivity of the jet rapidity
distribution to the gluon distribution function in the proton. We then assess
the sensitivity of various photon + jet correlation observables to the photon
fragmentation functions. We argue that RHIC data on photon-jet correlations can
be used to constrain the photon fragmentation functions in a region which was
barely accessible in LEP experiments.Comment: 23 pages, 9 figure
Preparation and characterization of novel substrates of insulin proteinase (EC 3.4.99.45)
An examination of business occupier relocation decision making : distinguishing small and large firm behaviour
This paper explores how business occupiers decide whether and where to relocate. It captures the experience and behaviour of a range of sizes and types of business occupier and subjects their decision-making processes to detailed scrutiny. A linear three-stage decision model is used to sequence and structure interviews with individuals who have intimate involvement with the relocation of 28 firms and organizations in Tyne and Wear, in the north-east of England. The 'constant comparative' method is used to analyse the interview data, from which emerges 18 key concepts, comprising 51 characteristic components. Using an axial approach, these are organized into 10 cross-cutting themes that represent the main areas of consideration or influence on the thinking of the people involved in determining whether a firm or organization should relocate and, if so, where to. The resulting analysis finds that organizations adopt varying degrees of sophistication when making relocation decisions; small firms are more inclined to make decisions based on constrained information; larger organizations adopt a more complex approach. Regardless of firm size, key individuals exert considerable influence over the decision-making process and its outcome
QCD
We discuss issues of QCD at the LHC including parton distributions, Monte
Carlo event generators, the available next-to-leading order calculations,
resummation, photon production, small x physics, double parton scattering, and
backgrounds to Higgs production.Comment: 115 pages, Latex, 47 figures, to appear in the Report of the ``1999
CERN Workshop on SM Physics (and more) at the LHC'', S. Catani, M. Dittmar,
D. Soper, W.J. Stirling, S. Tapprogge (convenors
Photon-pair jet production via gluon fusion at the LHC
Photon-pair direct or jet-associated productions are important for relevant
standard model measurement, Higgs and new physics searches at the LHC. The
loop-induced gluon-fusion process gg -> \gamma\gamma g, which although formally
contributes only at the next-to-next-to-leading order to \gamma\gamma j
productions, may get enhanced by the large gluon flux at the LHC. We have
checked and confirmed previous results on gg -> \gamma\gamma, \gamma\gamma g at
one loop, using now the traditional Feynman diagram based approach and taking
into account the quark mass effects, and further updated them for the 7 and 14
TeV LHC with new inputs and settings. We provide the details and results of the
calculations, which involves manipulation of rank-5 pentagon integrals. Our
results show that the gluon-fusion process can contribute about 10% of the Born
result, especially at small M_{\gamma\gamma} and PT_{\gamma\gamma}, and
increase further the overall scale uncertainty. Top quark loop effects are
examined in detail, which shows importance near or above the threshold
M_{\gamma\gamma} \gsim 2m_t.Comment: 10 pages, 5 figure
Direct photon cross sections in proton-proton and antiproton-proton interactions at GeV
We report results on inclusive direct photon , and production in both pp and \={p}p interactions at GeV in the transverse momentum range { GeV/} and rapidity range \mbox{}. The data were collected between 1988 and 1990 by the UA6 experiment at CERN, which employed an internal gas jet target in the S\={p}pS collider. The inclusive direct photon cross sections and the cross section difference \mbox{} expressed as functions of are compared w ith next-to-leading order QCD predictions
Parton fragmentation in the vacuum and in the medium
We present the mini-proceedings of the workshop on ``Parton fragmentation in
the vacuum and in the medium'' held at the European Centre for Theoretical
Studies in Nuclear Physics and Related Areas (ECT*, Trento) in February 2008.
The workshop gathered both theorists and experimentalists to discuss the
current status of investigations of quark and gluon fragmentation into hadrons
at different accelerator facilities (LEP, B-factories, JLab, HERA, RHIC, and
Tevatron) as well as preparations for extension of these studies at the LHC.
The main physics topics covered were: (i) light-quark and gluon fragmentation
in the vacuum including theoretical (global fits analyses and MLLA) and
experimental (data from e+e-, p-p, e-p collisions) aspects, (ii) strange and
heavy-quark fragmentation, (iii) parton fragmentation in cold QCD matter
(nuclear DIS), and (iv) medium-modified fragmentation in hot and dense QCD
matter (high-energy nucleus-nucleus collisions). These mini-proceedings consist
of an introduction and short summaries of the talks presented at the meeting.Comment: 43 pages, mini-proceedings Workshop ECT*, Trento, Feb. 25 - 29, 200
The histone deacetylase inhibitor Trichostatin A modulates CD4+ T cell responses
BACKGROUND: Histone deacetylase inhibitors (HDACIs) induce hyperacetylation of core histones modulating chromatin structure and affecting gene expression. These compounds are also able to induce growth arrest, cell differentiation, and apoptotic cell death of tumor cells in vitro as well as in vivo. Even though several genes modulated by HDAC inhibition have been identified, those genes clearly responsible for the biological effects of these drugs have remained elusive. We investigated the pharmacological effect of the HDACI and potential anti-cancer agent Trichostatin A (TSA) on primary T cells. METHODS: To ascertain the effect of TSA on resting and activated T cells we used a model system where an enriched cell population consisting of primary T-cells was stimulated in vitro with immobilized anti-CD3/anti-CD28 antibodies whilst exposed to pharmacological concentrations of Trichostatin A. RESULTS: We found that this drug causes a rapid decline in cytokine expression, accumulation of cells in the G(1 )phase of the cell cycle, and induces apoptotic cell death. The mitochondrial respiratory chain (MRC) plays a critical role in the apoptotic response to TSA, as dissipation of mitochondrial membrane potential and reactive oxygen species (ROS) scavengers block TSA-induced T-cell death. Treatment of T cells with TSA results in the altered expression of a subset of genes involved in T cell responses, as assessed by microarray gene expression profiling. We also observed up- as well as down-regulation of various costimulatory/adhesion molecules, such as CD28 and CD154, important for T-cell function. CONCLUSIONS: Taken together, our findings indicate that HDAC inhibitors have an immunomodulatory potential that may contribute to the potency and specificity of these antineoplastic compounds and might be useful in the treatment of autoimmune disorders
Are luminescent bacteria suitable for online detection and monitoring of toxic compounds in drinking water and its sources?
Biosensors based on luminescent bacteria may be valuable tools to monitor the chemical quality and safety of surface and drinking water. In this review, an overview is presented of the recombinant strains available that harbour the bacterial luciferase genes luxCDABE, and which may be used in an online biosensor for water quality monitoring. Many bacterial strains have been described for the detection of a broad range of toxicity parameters, including DNA damage, protein damage, membrane damage, oxidative stress, organic pollutants, and heavy metals. Most lux strains have sensitivities with detection limits ranging from milligrams per litre to micrograms per litre, usually with higher sensitivities in compound-specific strains. Although the sensitivity of lux strains can be enhanced by various molecular manipulations, most reported detection thresholds are still too high to detect levels of individual contaminants as they occur nowadays in European drinking waters. However, lux strains sensing specific toxic effects have the advantage of being able to respond to mixtures of contaminants inducing the same effect, and thus could be used as a sensor for the sum effect, including the effect of compounds that are as yet not identified by chemical analysis. An evaluation of the suitability of lux strains for monitoring surface and drinking water is therefore provided
The NOMAD Experiment at the CERN SPS
The NOMAD experiment is a short base-line search for Îœ<sub>ÎŒ</sub> â Îœ<sub>Ï</sub> oscillations in the CERN neutrino beam. The Îœ<sub>Ï</sub>'s are searched for through their charged current interactions followed by the observation of the resulting Ïâ through its electronic, muonic or hadronic decays. These decays are recognized using kinematical criteria necessitating the use of a light target which enables the reconstruction of individual particles produced in the neutrino interactions. This paper describes the various components of the NOMAD detector: the target and muon drift chambers, the electromagnetic and hadronic calorimeters, the preshower and transition radiation detectors and the veto and trigger scintillation counters. The beam and data acquisition system are also described. The quality of the reconstruction and individual particles is demonstrated through the ability of NOMAD to observe K<sub>s</sub><sup>0</sup>'s, Î<sup>0</sup>'s and Ï<sup>0</sup>'s. Finally, the observation of Ïâ through its electronic decay being one of the most promising channels in the search, the identification of electrons in NOMAD is discussed
- âŠ