230 research outputs found

    Odd C-P contributions to diffractive processes

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    We investigate contributions to diffractive scattering, which are odd under C- and P-parity. Comparison of p-pˉ\bar p and p-p scattering indicates that these odderon contributions are very small and we show how a diquark clustering in the proton can explain this effect. A good probe for the odderon exchange is the photo- and electroproduction of pseudo-scalar mesons. We concentrate on the pi^0 and show that the quasi elastic pi^0-production is again strongly suppressed for a diquark structure of the proton whereas the cross sections for diffractive proton dissociation are larger by orders of magnitude and rather independent of the proton structure.Comment: 18 pages, LaTex2e, graphicx package, 14 eps figures include

    Influence of oil activity and sheep ranching on plant cover in the arid and semi-arid region of Patagonia, Argentina

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    La Geografía como ciencia ha provisto el mayor cuerpo teórico para el estudio de las configuraciones que se producen sobre el espacio geográfico. La generación de cartografía que representa las cubiertas de suelo es uno de los usos más importantes de la percepción remota. Se seleccionaron polígonos, con actividad petrolera y ganadera, en las siguientes unidades de paisaje: cañadones, pampas y valles. Los polígonos se utilizaron para evaluar cambios multi-tempo-rales de las cubiertas de suelo y las comunidades vegetales en un período de 15 años. Se realizaron clasificaciones supervisadas y análisis de métricas de paisaje para examinar las posibles causas de estos cambios comparando: i) polígonos sin actividad petrolera ni ganadera (testigo), ii) con actividad petrolera y ganadera, iii) con actividad petrolera y sin actividad ganadera, y iv) sin actividad petrolera y con actividad ganadera. Los resultados obtenidos indicaron que la densidad de parches, el borde total, la densidad de borde y el índice de división de los fragmen-tos aumentaron en las tres unidades de paisaje, entre 2001 y 2016. El índice de contagio, en cambio, disminuyó. Se observó un incremento del suelo desnudo en las pampas y en los valles occidentales, con un retroceso de las comunidades vegetales dominantes. La densidad de parches en los sitios sin disturbios fue la menor, y en los sitios con ambos disturbios actuando simultáneamente fue máxima. En los sitios sin disturbio el tamaño efectivo de malla fue máximo, mientras que en los sitios con algún disturbio fue menor. Al analizar el efecto del disturbio sobre los elementos del paisaje se observó que su presencia genera la mayor densidad de parches y la mínima conectividad. Los resultados muestran que se produjo un proceso de frag-mentación en las coberturas del suelo direccionados por la explotación petrolera y la ganadería ovina, que disminuyen el tamaño de los parches y, por lo tanto, la densidad de los mismos por unidad de superficie.The Geography has provided the greatest theoretical body for the study of the configurations that occur over the geographical space. The generation of cartography that represents ground cover is one of the most important uses of remote sensing. Polygons were selected, with oil and livestock activity, in the landscape units: coastal canyons, plateaus and western valleys. The polygons were used to evaluate multi-temporal changes in land cover and plant communities over a period of 15 years. Supervised classifications and analysis of landscape metrics were made to examine the possible causes of these changes by comparing: i) polygons without oil or livestock activity (control), ii) polygons with oil and livestock activity, iii) polygons with oil activity and without livestock activity, and iv) polygons without oil activity and livestock activity. The results obtained indicated that the density of patches, the total edge, the edge density and the division index of the fragments increased in the three landscape units, between 2001 and 2016. The contagion index, however, decreased. An increase in bare soil was observed in the plateaus and in the western valleys, with a regression of the dominant plant communities. The density of patches in the sites without disturbance was the lowest, and in the sites with both disturbances acting simultaneously was maximum. In the sites without disturbance the effective mesh size was maximum, while in the sites with some disturbance it was smaller. When analyzing the effect of the disturbance on the elements of the landscape it was observed that the presence of the disturbance generates the highest density of patches and the minimum connectivity. The results show that there was a process of fragmentation in the coverage of the soil directed by the oil exploitation and sheep farming, which decrease the size of the patches and, therefore, the density of the same per unit area.Fil: Buzzi, Mariana Andrea. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ciencias Naturales y Ciencias de la Salud - Sede Puerto Madryn. Departamento de Biología y Ambiente; ArgentinaFil: Rueter, Barbara Lisa. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ciencias Naturales y Ciencias de la Salud - Sede Puerto Madryn. Departamento de Biología y Ambiente; ArgentinaFil: Ghermandi, Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Maldonado, F.. Universidad Nacional de la Patagonia. Facultad de Ciencias Naturales. Sede Puerto Madryn; Argentin

    Decomposition of the QCD String into Dipoles and Unintegrated Gluon Distributions

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    We present the perturbative and non-perturbative QCD structure of the dipole-dipole scattering amplitude in momentum space. The perturbative contribution is described by two-gluon exchange and the non-perturbative contribution by the stochastic vacuum model which leads to confinement of the quark and antiquark in the dipole via a string of color fields. This QCD string gives important non-perturbative contributions to high-energy reactions. A new structure different from the perturbative dipole factors is found in the string-string scattering amplitude. The string can be represented as an integral over stringless dipoles with a given dipole number density. This decomposition of the QCD string into dipoles allows us to calculate the unintegrated gluon distribution of hadrons and photons from the dipole-hadron and dipole-photon cross section via kT-factorization.Comment: 43 pages, 14 figure

    Epistemic Beliefs: Relationship to Future Expectancies and Quality of Life in Cancer Patients.

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    CONTEXT: Expectations about the future (future expectancies) are important determinants of psychological well-being among cancer patients, but the strategies patients use to maintain positive and cope with negative expectancies are incompletely understood. OBJECTIVES: To obtain preliminary evidence on the potential role of one strategy for managing future expectancies: the adoption of epistemic beliefs in fundamental limits to medical knowledge. METHODS: A sample of 1307 primarily advanced-stage cancer patients participating in a genomic tumor testing study in community oncology practices completed measures of epistemic beliefs, positive future expectancies, and mental and physical health-related quality of life (HRQOL). Descriptive and linear regression analyses were conducted to assess the relationships between these factors and test two hypotheses: 1) epistemic beliefs affirming fundamental limits to medical knowledge ( fallibilistic epistemic beliefs ) are associated with positive future expectancies and mental HRQOL, and 2) positive future expectancies mediate this association. RESULTS: Participants reported relatively high beliefs in limits to medical knowledge (M = 2.94, s.d.=.67) and positive future expectancies (M = 3.01, s.d.=.62) (range 0-4), and relatively low mental and physical HRQOL. Consistent with hypotheses, fallibilistic epistemic beliefs were associated with positive future expectancies (b = 0.11, SE=.03, P\u3c 0.001) and greater mental HRQOL (b = 0.99, SE=.34, P = 0.004); positive expectancies also mediated the association between epistemic beliefs and mental HRQOL (Sobel Z=4.27, P\u3c0.001). CONCLUSIONS: Epistemic beliefs in limits to medical knowledge are associated with positive future expectancies and greater mental HRQOL; positive expectancies mediate the association between epistemic beliefs and HRQOL. More research is needed to confirm these relationships and elucidate their causal mechanisms

    Citrobacter rodentium NleB Protein Inhibits Tumor Necrosis Factor (TNF) Receptor-associated Factor 3 (TRAF3) Ubiquitination to Reduce Host Type I Interferon Production

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    Citation: Gao, X. F., Pham, T. H., Feuerbacher, L. A., Chen, K. M., Hays, M. P., Singh, G., . . . Hardwidge, P. R. (2016). Citrobacter rodentium NleB Protein Inhibits Tumor Necrosis Factor (TNF) Receptor-associated Factor 3 (TRAF3) Ubiquitination to Reduce Host Type I Interferon Production. Journal of Biological Chemistry, 291(35), 18232-18238. doi:10.1074/jbc.M116.738278Interferon signaling plays important roles in both intestinal homeostasis and in the host response to pathogen infection. The extent to which bacterial pathogens inhibit this host pathway is an understudied area of investigation. We characterized Citrobacter rodentium strains bearing deletions in individual type III secretion system effector genes to determine whether this pathogen inhibits the host type I IFN response and which effector is responsible. The NleB effector limited host IFN- production by inhibiting Lys(63)-linked ubiquitination of TNF receptor-associated factor 3 (TRAF3). Inhibition was dependent on the glycosyltransferase activity of NleB. GAPDH, a target of NleB during infection, bound to TRAF3 and was required for maximal TRAF3 ubiquitination. NleB glycosyltransferase activity inhibited GAPDH-TRAF3 binding, resulting in reduced TRAF3 ubiquitination. Collectively, our data reveal important interplay between GAPDH and TRAF3 and suggest a mechanism by which the NleB effector inhibits type I IFN signaling

    Gamma(*)Gamma(*) reaction at high energies

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    The energy available for gamma(*)gamma(*) physics at LEP2 is opening a new window on the study of diffractive phenomena, both non-perturbative and perturbative. We discuss some of the uncertainties and problems connected with the experimental measurements and their interpretation.Comment: 6 pages, 6 figures, submitted to proceedings of the Durham Collider Workshop, 22-26 September 199

    Dark matter direct detection from new interactions in models with spin-two mediators

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    We consider models where a massive spin-two resonance acts as the mediator between Dark Matter (DM) and the SM particles through the energy-momentum tensor. We examine the effective theory for fermion, vector and scalar DM generated in these models and find novel types of DM-SM interaction never considered before. We identify the effective interactions between DM and the SM quarks when the mediator is integrated out, and match them to the gravitational form factors relevant for spin-independent DM-nucleon scattering. We also discuss the interplay between DM relic density conditions, direct detection bounds and collider searches for the spin-two mediator

    Confining QCD Strings, Casimir Scaling, and a Euclidean Approach to High-Energy Scattering

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    We compute the chromo-field distributions of static color-dipoles in the fundamental and adjoint representation of SU(Nc) in the loop-loop correlation model and find Casimir scaling in agreement with recent lattice results. Our model combines perturbative gluon exchange with the non-perturbative stochastic vacuum model which leads to confinement of the color-charges in the dipole via a string of color-fields. We compute the energy stored in the confining string and use low-energy theorems to show consistency with the static quark-antiquark potential. We generalize Meggiolaro's analytic continuation from parton-parton to gauge-invariant dipole-dipole scattering and obtain a Euclidean approach to high-energy scattering that allows us in principle to calculate S-matrix elements directly in lattice simulations of QCD. We apply this approach and compute the S-matrix element for high-energy dipole-dipole scattering with the presented Euclidean loop-loop correlation model. The result confirms the analytic continuation of the gluon field strength correlator used in all earlier applications of the stochastic vacuum model to high-energy scattering.Comment: 65 pages, 13 figures, extended and revised version to be published in Phys. Rev. D (results unchanged, 2 new figures, 1 new table, additional discussions in Sec.2.3 and Sec.5, new appendix on the non-Abelian Stokes theorem, old Appendix A -> Sec.3, several references added

    Local endothelial complement activation reverses endothelial quiescence, enabling t-cell homing, and tumor control during t-cell immunotherapy.

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    Cancer immunotherapy relies upon the ability of T cells to infiltrate tumors. The endothelium constitutes a barrier between the tumor and effector T cells, and the ability to manipulate local vascular permeability could be translated into effective immunotherapy. Here, we show that in the context of adoptive T cell therapy, antitumor T cells, delivered at high enough doses, can overcome the endothelial barrier and infiltrate tumors, a process that requires local production of C3, complement activation on tumor endothelium and release of C5a. C5a, in turn, acts on endothelial cells promoting the upregulation of adhesion molecules and T-cell homing. Genetic deletion of C3 or the C5a receptor 1 (C5aR1), and pharmacological blockade of C5aR1, impaired the ability of T cells to overcome the endothelial barrier, infiltrate tumors, and control tumor progression in vivo, while genetic chimera mice demonstrated that C3 and C5aR1 expression by tumor stroma, and not leukocytes, governs T cell homing, acting on the local endothelium. In vitro, endothelial C3 and C5a expressions were required for endothelial activation by type 1 cytokines. Our data indicate that effective immunotherapy is a consequence of successful homing of T cells in response to local complement activation, which disrupts the tumor endothelial barrier
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