740 research outputs found
Determination of fragmentation functions and their uncertainties from e+ + e- -> h + X data
Fragmentation functions are determined for pions, kaons, and nucleons by a
global analysis of charged-hadron production data in electron-positron
annihilation. The optimum functions are obtained in both leading order (LO) and
next-to-leading order (NLO) of alpha_s. It is important that uncertainties of
the fragmentation functions are estimated in this work by the Hessian method.
We found that the uncertainties are large at small Q^2 and that they are
generally reduced in the NLO in comparison with the LO ones. We supply a code
for calculating the fragmentation functions and their uncertainties for the
pions, kaons, and nucleons at given z and Q^2.Comment: 4 pages, LaTeX, 5 eps files, to be published in AIP proceedings of
the 17th International Spin Physics Symposium (SPIN2006), Oct. 2-7, 2006,
Kyoto, Japa
Low-mass lepton pair production at large transverse momentum
We study the transverse momentum distribution of low-mass lepton pairs
produced in hadronic scattering, using the perturbative QCD factorization
approach. We argue that the distribution at large transverse momentum, , with the pair's invariant mass as low as , can be systematically factorized into universal
parton-to-lepton pair fragmentation functions, parton distributions, and
perturbatively calculable partonic hard parts evaluated at a short distance
scale . We introduce a model for the input lepton pair
fragmentation functions at a scale GeV, which are then evolved
perturbatively to scales relevant at RHIC. Using the evolved fragmentation
functions, we calculate the transverse momentum distributions in hadron-hadron,
hadron-nucleus, and nucleus-nucleus collisions at RHIC. We also discuss the
sensitivity of the transverse momentum distribution of low-mass lepton pairs to
the gluon distribution.Comment: 16 pages, 11 figures, revised version to appear in Phys. Rev.
A Next-to-Leading-Order Study of Dihadron Production
The production of pairs of hadrons in hadronic collisions is studied using a
next-to-leading-order Monte Carlo program based on the phase space slicing
technique. Up-to-date fragmentation functions based on fits to LEP data are
employed, together with several versions of current parton distribution
functions. Good agreement is found with data for the dihadron mass
distribution. A comparison is also made with data for the dihadron angular
distribution. The scale dependence of the predictions and the dependence on the
choices made for the fragmentation and parton distribution functions are also
presented. The good agreement between theory and experiment is contrasted to
the case for single production where significant deviations between
theory and experiment have been observed.Comment: 22 pages, 15 figures; 3 references added, one figure modified for
clarit
The potential for soybean to diversify the production of plant-based protein in the UK
Soybean (Glycine max) offers an important source of plant-based protein. Currently much of Europe’s soybean is imported, but there are strong economic and agronomic arguments for boosting local production. Soybean is grown in central and eastern Europe but is less favoured in the North due to climate. We conducted field trials across three seasons and two sites in the UK to test the viability of early-maturing soybean varieties and used the data from these trials to calibrate and validate the Rothamsted Landscape Model. Once validated, the model was used to predict the probability soybean would mature and the associated yield for 26 sites across the UK based on weather data under current, near-future (2041-60) and far-future (2081-2100) climate. Two representative concentration pathways, a midrange mitigation scenario (RCP4.5) and a high emission scenario (RCP8.5) were also explored. Our analysis revealed that under current climate early maturing varieties will mature in the south of the UK, but the probability of failure increases with latitude. Of the 26 sites considered, only at one did soybean mature for every realisation. Predicted expected yields ranged between 1.39 t ha-1 and 1.95 t ha-1 across sites. Under climate change these varieties are likely to mature as far north as southern Scotland. With greater levels of CO2, yield is predicted to increase by as much as 0.5 t ha-1 at some sites in the far future, but this is tempered by other effects of climate change meaning that for most sites no meaningful increase in yield is expected. We conclude that soybean is likely to be a viable crop in the UK and for similar climates at similar latitudes in Northern Europe in the future but that for yields to be economically attractive for local markets, varieties must be chosen to align with the growing season
Adenovirus type 5 E4 Orf3 protein targets promyelocytic leukaemia (PML) protein nuclear domains for disruption via a sequence in PML isoform II that is predicted as a protein interaction site by bioinformatic analysis
Human adenovirus type 5 infection causes the disruption of structures in the cell nucleus termed promyelocytic leukaemia (PML) protein nuclear domains or ND10, which contain the PML protein as a critical component. This disruption is achieved through the action of the viral E4 Orf3 protein, which forms track-like nuclear structures that associate with the PML protein. This association is mediated by a direct interaction of Orf3 with a specific PML isoform, PMLII. We show here that the Orf3 interaction properties of PMLII are conferred by a 40 aa residue segment of the unique C-terminal domain of the protein. This segment was sufficient to confer interaction on a heterologous protein. The analysis was informed by prior application of a bioinformatic tool for the prediction of potential protein interaction sites within unstructured protein sequences (predictors of naturally disordered region analysis; PONDR). This tool predicted three potential molecular recognition elements (MoRE) within the C-terminal domain of PMLII, one of which was found to form the core of the Orf3 interaction site, thus demonstrating the utility of this approach. The sequence of the mapped Orf3-binding site on PML protein was found to be relatively poorly conserved across other species; however, the overall organization of MoREs within unstructured sequence was retained, suggesting the potential for conservation of functional interactions
Effect of conventional and ultra-high dose rate "FLASH" irradiations on preclinical tumour models: A systematic analysis: Tumour response to CONV and UHDR irradiation.
When compared to conventional dose rate irradiation (CONV), ultra-high dose rate irradiation (UHDR) has shown superior normal tissue sparing. However, a clinically relevant widening of the therapeutic window by UHDR, termed "FLASH effect", also depends on the tumour toxicity obtained by UHDR. Based on a combined analysis of published literature, the current study re-examines the hypothesis of tumour isoefficacy for UHDR versus CONV and aims to identify potential knowledge gaps to inspire future in vivo studies.
A systematic literature search identified publications assessing in vivo tumour responses comparing UHDR and CONV. Qualitative and quantitative analyses were performed, including combined analyses of tumour growth and survival data.
We identified 66 data sets from 15 publications that compared UHDR and CONV for tumour efficacy. The median number of animals per group was 9 (range: 3-15) and the median follow-up period was 30.5 (range: 11-230) days after the first irradiation. Tumour growth assays were the predominant model used. Combined statistical analyses of tumour growth and survival data are consistent with UHDR isoefficacy compared to CONV. Only one study determined tumour-controlling dose (TCD <sub>50</sub> ) and reported statistically non-significant differences.
The combined quantitative analyses of tumour responses support the assumption of UHDR isoefficacy compared to CONV. However, the comparisons are primarily based on heterogeneous tumour growth assays with limited numbers of animals and short follow-up, and most studies do not assess long-term tumour control probability. Therefore, the assays may be insensitive in resolving smaller response differences, such as responses of radio-resistant tumour sub-clones. Hence, tumour cure experiments, including additional TCD <sub>50</sub> experiments, are needed to confirm the assumption of isoeffectiveness in curative settings
Measures Matter: Scales for Adaptation, Cultural Distance, and Acculturation Orientation Revisited
Building upon existing measures, four new brief acculturation scales are presented, measuring sociocultural adaptation, psychological adaptation, perceived cultural distance, and acculturation orientation. Following good scale reliability in initial samples, the English scales were translated into nine different languages (Chinese, French, German, Italian, Japanese, Portuguese, Spanish, Thai, and Turkish). The translated scales were administered to a large sample of sojourners (N = 1,929), demonstrating good reliability and adequate structural equivalence across languages. In line with existing theory, sociocultural adaptation and psychological adaptation were positively correlated, and showed a negative association with perceived cultural distance. General measures of well-being were correlated with adaptation and distance, with better adaptation relating to higher well-being, and more distance relating to lower well-being. Acculturation orientation toward the home and host culture were measured separately and a weak negative correlation was found between the two, supporting their independence. Arguing against dichotomization, these subscales were analyzed as continuous variables. Regression analysis showed sojourners to be better adapted, if they were oriented more toward the host culture and less toward the home culture. These new scales are proposed as alternatives to existing measures
Thermal Photons in Strong Interactions
A brief survey is given on the current status of evaluating thermal
production of photons from a strongly interacting medium. Emphasis is put on
recent progress in assessing equilibrium emission rates in both hadronic and
quark-gluon matter. We also give an update on the status of comparing
theoretical calculations with experimental data from heavy-ion collisions at
the SPS, as well as prospects for RHIC. Finally, applications of photon rate
calculations to colorsuperconducting quark matter are discussed.Comment: Brief Review for Mod. Phys. Lett A, 15 pages latex incl. 12 ps/eps
figs and style file ws-mpla.cl
Investigating the high energy QCD approaches for prompt photon production at the LHC
We investigate the rapidity and transverse momentum distributions of the
prompt photon production at the CERN LHC energies considering the current
perturbative QCD approaches for this scattering process. Namely, we compare the
predictions from the usual NLO pQCD calculations to the the color dipole
formalism, using distinct dipole cross sections. Special attention is paid to
parton saturation models at high energies, which are expected to be important
at the forward rapidities in pp collisions at the LHC.Comment: Contribution to the proceedings of the 3rd International Conference
on Hard and Electro-Magnetic Probes of High-Energy Nuclear Collisions (Hard
Probes 2008), 8-14 June 2008, Illa da Toxa (Galicia-Spain). Talk presented by
M.V.T. Machad
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