Severe Hepatic Trauma : Nonoperative Management, Definitive Repair, or Damage Control Surgery?

Peer reviewe

Weak evidence of regeneration habitat but strong evidence of regeneration niche for a leguminous shrub

The identification of an ecological niche specific to the regeneration phase has mobilised significant attention. However, the importance of the regeneration niche concept remains unclear. Our main objective was to study the existence of such a regeneration niche for a leguminous shrub, Ulex europaeus. This study was carried out in southwest France in the context of water and nutrient stresses (mainly phosphorus limitation) due to the presence of nutrient-poor sandy soils. We analysed the regeneration of the species from the germination of seeds and emergence of new seedlings until the seedlings reached young shrub size. Our design included a P fertilisation treatment. We also investigated microsite characteristics (micro-topography and vegetation development) as they can interact with meteorological conditions and determine water availability for seeds and seedlings. We found that P availability controlled seedling growth and the time necessary to reach young shrub size. Water availability appeared to impact the species germination and seedlings survival. We also found that P and water availability depended on the interactions between microsite characteristics and climatic variations. Finally we found evidence that P and water availability are important ecological factors shaping the regeneration niche of the species, but we found weak evidence that any microsite would be appropriate for the regeneration of the species in the long term. Future studies regarding regeneration niches need to distinguish more clearly the ecological factors important for regeneration (the regeneration niche per se) and the physical world where the seedlings appear and develop (the regeneration habitat)

Jet production in highQ 2 deep-inelastic ep scattering at HERA

Two-jet production in deep-inelastic electron-proton scattering has been studied for $160<Q^2<1280$~GeV$^2$, $0.01<x<0.1$ and $0.04<y<0.95$ with the ZEUS detector at HERA. The kinematic properties of the jets and the jet production rates are presented. The partonic scaling variables of the two-jet system and the rate of two-jet production are compared to perturbative next-to-leading order QCD calculations.Comment: 26 pages, latex, 9 figures appended as uuencoded fil

Observation of events with a large rapidity gap in deep inelastic scattering at HERA

In deep inelastic, neutral current scattering of electrons and protons at &#8730; s = 296 GeV, we observe in the ZEUS detector events with a large rapidity gap in the hadronic final state. They occur in the region of small Bjorken x and are observed up to Q&lt;sup&gt;2&lt;/sup&gt; of 100 GeV&lt;sup&gt;2&lt;/sup&gt;. They account for about 5% of the events with Q&lt;sup&gt;2&lt;/sup&gt; &#8805; 10 GeV&lt;sup&gt;2&lt;/sup&gt;. Their general properties are inconsistent with the dominant mechanism of deep inelastic scattering, where color is transferred between the scattered quark and the proton remnant, and suggest that the underlying production mechanism is the diffractive dissociation of the virtual photon

Diffractive hard photoproduction at HERA and evidence for the gluon content of the pomeron

Inclusive jet cross sections for events with a large rapidity gap with respect to the proton direction from the reaction $ep \rightarrow jet \; + \; X$ with quasi-real photons have been measured with the ZEUS detector. The cross sections refer to jets with transverse energies $E_T^{jet}>8$~GeV. The data show the characteristics of a diffractive process mediated by pomeron exchange. Assuming that the events are due to the exchange of a pomeron with partonic structure, the quark and gluon content of the pomeron is probed at a scale $\sim (E_T^{jet})^2$. A comparison of the measurements with model predictions based on QCD plus Regge phenomenology requires a contribution of partons with a hard momentum density in the pomeron. A combined analysis of the jet cross sections and recent ZEUS measurements of the diffractive structure function in deep inelastic scattering gives the first experimental evidence for the gluon content of the pomeron in diffractive hard scattering processes. The data indicate that between 30\% and 80\% of the momentum of the pomeron carried by partons is due to hard gluons.Comment: 25 pages, latex, 4 figures appended as uuencoded file. No change w.r.t. previous version (just avoiding warning latex messages while processing

Measurement of alpha-s from jet rates in deep inelastic scattering at HERA

Jet production in deep inelastic scattering for $120<Q^2<3600$~GeV$^2$ has been studied using data from an integrated luminosity of 3.2~pb$^{-1}$ collected with the ZEUS detector at HERA. Jets are identified with the JADE algorithm. A cut on the angular distribution of parton emission in the $\gamma^*$-parton centre-of-mass system minimises the experimental and theoretical uncertainties in the determination of the jet rates. The jet rates, when compared to ${\cal O}$($\alpha_{s}$^2$) perturbative QCD calculations, allow a precise determination of$\alpha_{s}(Q)$in three$Q^2$-intervals. The values are consistent with a running of$\alpha_{s}(Q)$, as expected from QCD. Extrapolating to$Q=M_{Z^0}$yields$\alpha_{s}(M_{Z^0}) = 0.117~\pm~0.005~(stat)~^{+0.004}_{-0.005}~(syst_{exp})~ ~{\pm~0.007}~(syst_{theory})$.Comment: 22 pages, latex, 4 figures appended as uuencoded fil

Inclusive jet differential cross-sections in photoproduction at HERA

Inclusive jet differential cross sections for the reaction ep --> jet + X at Q(2) below 4 GeV2 have been measured with the ZEUS detector at HERA using an integrated luminosity of 0.55 pb(-1). These cross sections are given in the kinematic region 0.2 < y < 0.85, for jet pseudorapidities in the ep-laboratory range -1 < eta(jet) < 2 and refer to jets at the hadron level with a cone radius of one unit in the eta - phi plane. These results correspond to quasi-real photoproduction at centre-of-mass energies in the range 130-270 GeV and, approximately, for jet pseudorapidities in the interval -3 < eta(jet)(gamma p CMS) < 0. These measurements cover a new kinematic regime of the partonic structure of the photon, at typical scales up to similar to 300 GeV2 and photon fractional momenta down to x(y) similar to 10(-2). Leading logarithm parton shower Monte Carlo calculations, which include both resolved and direct processes and use the predictions of currently available parametrisations of the photon parton distributions, describe in general the shape and magnitude of the measured eta(jet) and E(T)(jet) distributions