986 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
Ti–Si–C thin films produced by magnetron sputtering : correlation between physical properties, mechanical properties and tribological behavior
Ti–Si–C thin films were deposited onto silicon, stainless steel and high-speed steel substrates by magnetron sputtering, using different chamber configurations. The composition of the produced films was obtained by Electron Probe Micro-Analysis (EPMA) and the structure by X-ray diffraction
(XRD). The hardness and residual stresses were obtained by depth-sensing indentation and substrate deflection measurements (using Stoney’s equation), respectively. The tribological behavior of the produced films was studied by pin-on-disc. The increase of the concentration of non-metallic elements (carbon and silicon) caused significant changes in their properties. Structural analysis
revealed the possibility of the coexistence of different phases in the prepared films, namely Ti metallic phase ( alpha-Ti or beta-Ti) in the films with higher Ti content. The coatings with highest carbon contents, exhibited mainly a sub-stoichiometric fcc NaCl TiC-type structure. These structural changes were
also confirmed by resistivity measurements, whose values ranged from 10E3 Ohm/sq for low non-metal concentration, up to 10E6 Ohm /sq for the highest metalloid concentration. Astrong increase of hardness
and residual stresses was observed with the increase of the non-metal concentration in the films. The hardness (H) values ranged between 11 and 27 GPa, with a clear dependence on both crystalline structure and composition features. Following the mechanical behavior, the tribological results
showed similar trends, with both friction coefficients and wear revealing also a straight correlation with the composition and crystalline structure of the coatings
Optimization and thermal stability of TiAlN-Mo multilayers
In this work we focus on the optimization and thermal stability of nanocomposite TiAlN/Mo multilayers that were produced by reactive
magnetron sputtering on high-speed steel substrates, with modulation periods below 5 nm. These multilayers were annealed between 600–
900 ºC for 1 h in a vacuum furnace. Preliminary X-ray diffraction results reveal that these coatings are very stable up to 900 ºC, since the multilayer
chemical modulation is not severely affected. At intermediate annealing temperatures the modulation period decreases due to interdiffusion at
the interface, resulting in a thicker interface between metal/nitride and hence decreasing the thickness of those layers.Portuguese FCT/MCES scientific program
Tyrphostin AG 1024 modulates radiosensitivity in human breast cancer cells
Insulin-like growth factor-1 (IGF-1) plays an important growth-promoting effect by activating the PI3K/Akt signalling pathway, inhibiting apoptotic pathways and mediating mitogenic actions. Tyrphostin AG 1024, one selective inhibitor of IGF-1R, was used to evaluate effects on proliferation, radiosensitivity, and radiation-induced cell apoptosis in a human breast cancer cell line MCF-7. Exposure to Tyrphostin AG 1024 inhibited proliferation and induced apoptosis in a time-dependent manner, and the degree of growth inhibition for IC20 plus irradiation (4 Gy) was up to 50% compared to the control. Examination of Tyrphostin AG 1024 effects on radiation response demonstrated a marked enhancement in radiosensitivity and amplification of radiation-induced apoptosis. Western blot analysis indicated that Tyrphostin AG 1024-induced apoptosis was associated with a downregulation of expression of phospho-Akt1, increased expression of Bax, p53 and p21, and a decreased expression of bcl-2 expression, especially when combined with irradiation. To our knowledge, this is the first report showing that an IGF-1 inhibitor was able to markedly increase the response of tumour cells to ionizing radiation. These results suggest that Tyrphostin AG 1024 could be used as a potential therapeutic agent in combination with irradiation.   http://www.bjcancer.com © 2001 Cancer Research Campaig
Pour en finir avec le Bronze final ? Les haches à douille de type armoricain en France
A discussion about socket armorican bronze axes datation. They are from Ha D period (VII th & VIt h century B.C.)Révision de la datation des haches à douille de type armoricain, au seul Hallstatt D (VIIe-VIe s; av. J.-C.
Factorization and soft-gluon divergences in isolated-photon cross sections
We study the production of isolated photons in annihilation and give
the proof of the all-order factorization of the collinear singularities. These
singularities are absorbed in the standard fragmentation functions of partons
into a photon, while the effects of the isolation are consistently included in
the short-distance cross section. We compute this cross section at order \as
and show that it contains large double logarithms of the isolation parameters.
We explain the physical origin of these logarithms and discuss the possibility
to resum them to all orders in \as.Comment: 18 pages, LaTex, 2 eps figures, few modifications in the text,
results unchange
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
Direct photons in d+Au collisions at s_(NN)**(1/2)=200GeV with STAR
Results are presented of an ongoing analysis of direct photon production in
s_(NN)=200GeV deuteron-gold collisions with the STAR experiment at RHIC. A
significant excess of direct photons is observed near mid-rapidity 0<y<1 and
found to be consistent with next-to-leading order pQCD calculations including
the contribution from fragmentation photons.Comment: 4 pages, 4 figures, HotQuarks 200
Enquête sur la colibacillose du porcelet nouveau né
Renault Lucien, Le Bourhis Elizabeth, Maire Cl., Vaissaire Josée. Enquête sur la colibacillose du porcelet nouveau-né. In: Bulletin de l'Académie Vétérinaire de France tome 128 n°8, 1975. pp. 397-403
Measuring the Photon Fragmentation Function at HERA
The production of final state photons in deep inelastic scattering originates
from photon radiation off leptons or quarks involved in the scattering process.
Photon radiation off quarks involves a contribution from the quark-to-photon
fragmentation function, corresponding to the non-perturbative transition of a
hadronic jet into a single, highly energetic photon accompanied by some limited
hadronic activity. Up to now, this fragmentation function was measured only in
electron-positron annihilation at LEP. We demonstrate by a dedicated
parton-level calculation that a competitive measurement of the quark-to-photon
fragmentation function can be obtained in deep inelastic scattering at HERA.
Such a measurement can be obtained by studying the photon energy spectra in
-jet events, where denotes a hadronic jet containing a
highly energetic photon (the photon jet). Isolated photons are then defined
from the photon jet by imposing a minimal photon energy fraction. For this
so-called democratic clustering approach, we study the cross sections for
isolated -jet and -jet production as well as
for the inclusive isolated photon production in deep inelastic scattering.Comment: 23 pages, LaTe
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