243 research outputs found
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Geographies of Production I: Relationality revisited and the âpractice shiftâ in economic geography
This report considers recent developments and ongoing debates around relational economic geography, and a growing body work that has focused on economic practices as a means to better understand production processes and economic development. In particular it examines the critical reaction to relational thinking within the sub-discipline, and the nature of the debate about the degree to which relational work is - and needs to be - regarded as distinct from more traditional approaches to economic geography. It then considers how relational economic geography has become inflected towards an epistemological and methodological focus on practice. It argues that this engagement with economic practices provides the basis to respond to some of the limitations identified with earlier work, and opens up fruitful new potential for theorizing the nature of agency in the space economy
A full Next to Leading Order study of direct photon pair production in hadronic collisions
We discuss the production of photon pairs in hadronic collisions, from fixed
target to LHC energies. The study which follows is based on a QCD calculation
at full next-to-leading order accuracy, including single and double
fragmentation contributions, and implemented in the form of a general purpose
computer program of "partonic event generator" type. To illustrate the
possibilities of this code, we present the comparison with observables measured
by the WA70 and D0 collaborations, and some predictions for the irreducible
background to the search of Higgs bosons at LHC in the channel . We also discuss theoretical scale uncertainties for these predictions,
and examine several infrared sensitive situations which deserve further study.Comment: 45 pages Latex, 16 eps files plus some metafont files; replaced by
the version to appear in Eur. Phys. J.
A next-to-leading order study of photon-pion and pion pair hadro-production in the light of the Higgs boson search at the LHC
We discuss the production of photon-pion and pion pairs with a large
invariant mass at collider energies. We present a study based on a perturbative
QCD calculation at full next-to-leading order accuracy, implemented in the
computer programme DIPHOX. We give estimations for various observables, which
concern the reducible background to the Higgs boson search in the channel H -->
gamma gamma, in the mass range 80-140 GeV at the LHC. We critically discuss the
reliability of these estimates due to our imperfect knowledge of fragmentation
functions at high z and a subtle interplay between higher order corrections and
realistic experimental cuts. We conclude that, whereas the invariant mass
spectrum of photon-pion pairs is theoretically better under control, in the
dipion case large uncertainties remain.Comment: 26 pages Latex, 14 eps figures, replaced by published versio
A critical phenomenological study of inclusive photon production in hadronic collisions
We discuss fixed target and ISR inclusive photon production and attempt a
comparison between theory and experiments. The dependence of the theoretical
predictions on the structure functions, and on the renormalization and
factorization scales is investigated. The main result of this study is that the
data cannot be simultaneously fitted with a single set of scales and structure
functions. On the other hand, there is no need for an additional intrinsic
to force the agreement between QCD predictions and experiments, with
the possible exception of one data set. Since the data cover almost overlapping
kinematical ranges this raises the question of consistency among data sets. A
comparative discussion of some possible sources of experimental uncertainties
is sketched.Comment: 22 pages, 3 tables, 10 figures, Late
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
Retrograde optogenetic characterization of the pontospinal module of the locus coeruleus with a canine adenoviral vector
AbstractNoradrenergic neurons of the brainstem extend projections throughout the neuraxis to modulate a wide range of processes including attention, arousal, autonomic control and sensory processing. A spinal projection from the locus coeruleus (LC) is thought to regulate nociceptive processing. To characterize and selectively manipulate the pontospinal noradrenergic neurons in rats, we implemented a retrograde targeting strategy using a canine adenoviral vector to express channelrhodopsin2 (CAV2-PRS-ChR2-mCherry). LC microinjection of CAV2-PRS-ChR2-mCherry produced selective, stable, transduction of noradrenergic neurons allowing reliable opto-activation in vitro. The ChR2-transduced LC neurons were opto-identifiable in vivo and functional control was demonstrated for >6 months by evoked sleep-wake transitions. Spinal injection of CAV2-PRS-ChR2-mCherry retrogradely transduced pontine noradrenergic neurons, predominantly in the LC but also in A5 and A7. A pontospinal LC (ps:LC) module was identifiable, with somata located more ventrally within the nucleus and with a discrete subset of projection targets. These ps:LC neurons had distinct electrophysiological properties with shorter action potentials and smaller afterhyperpolarizations compared to neurons located in the core of the LC. In vivo recordings of ps:LC neurons showed a lower spontaneous firing frequency than those in the core and they were all excited by noxious stimuli. Using this CAV2-based approach we have demonstrated the ability to retrogradely target, characterise and optogenetically manipulate a central noradrenergic circuit and show that the ps:LC module forms a discrete unit.This article is part of a Special Issue entitled SI: Noradrenergic System
A critical phenomenological study of inclusive photon production in hadronic collisions
Abstract. We discuss fixed target and ISR inclusive photon production and attempt a comparison between theory and experiments. The dependence of the theoretical predictions on the structure functions, and on the renormalization and factorization scales is investigated. The main result of this study is that the data cannot be simultaneously fitted with a single set of scales and structure functions. On the other hand, there is no need for an additional primordial k T to force the agreement between QCD predictions and experiments, with the possible exception of one data set. Since the data cover almost overlapping kinematical ranges this raises the question of consistency among data sets. A comparative discussion of some possible sources of experimental uncertainties is sketched
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
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