3,191 research outputs found
Eikonal zeros in the momentum transfer space from proton-proton scattering: An empirical analysis
By means of improved empirical fits to the differential cross section data on
elastic scattering at GeV and making use of a
semi-analytical method, we determine the eikonal in the momentum transfer space
(the inverse scattering problem). This method allows the propagation of the
uncertainties from the fit parameters up to the extracted eikonal, providing
statistical evidence that the imaginary part of the eikonal (real part of the
opacity function) presents a zero (change of signal) in the momentum space, at
GeV. We discuss the implication of this change of
signal in the phenomenological context, showing that eikonal models with one
zero provide good descriptions of the differential cross sections in the full
momentum transfer range, but that is not the case for models without zero.
Empirical connections between the extracted eikonal and results from a recent
global analysis on the proton electric form factor are also discussed, in
special the Wu-Yang conjecture. In addition, we present a critical review on
the differential cross section data presently available at high energies.Comment: Two references and some misprints corrected, 22 pages; final version
to be published in Eur.Phys. J. C (2008
Tecnologias para o manejo de pragas iniciais em milho safrinha.
bitstream/item/65384/1/29903.pdfOrganizado por Gessi Ceccon e Luiz Alberto Staut; Palestra
The PI3K/AKT/mTOR canonical pathway and its alterations in cancer
La vía PI3K/AKT/mTOR participa en múltiples procesos celulares fundamentales para la célula. Algunas mutaciones genéticas de los componentes de esta vía se han asociado a diversas enfermedades humanas: las más importantes son los carcinomas de mama, tiroides y endometrio, el glioblastoma multiforme, el cáncer de próstata y los linfomas. La vía canónica PI3K/AKT/mTOR se ha estudiado ampliamente en los últimos años. Sin embargo, el conocimiento de la complejidad de sus componentes principales y su interrelación con los elementos de otras vías va en aumento. Por ello, es importantes actualizar cada cierto tiempo la información disponible para la comprensión de este mecanismo. Así mismo, se están y se han desarrollado numerosos ensayos con medicinas selectivas en búsqueda de un tratamiento más inteligente para las enfermedades asociadas a alteraciones de esta vía. Por tanto, realizamos una revisión de esta vía de transducción con el objetivo de tener una visión cercana de su funcionamiento, sus alteraciones y enumerar algunas moléculas promisorias para ser utilizadas en futuros tratamientos.The PI3K/AKT/mTOR pathway is involved in multiple cellular processes which are essential for the cells. Some genetic mutations of the components of this pathway have been associated with various human diseases, the most important of which are breast, thyroid and endometrium carcinomas; glioblastoma multiforme; prostate cancer and lymphomas. The PI3K/AKT/mTOR canonical pathway has been extensively studied in recent years. However, as the complexity of its main components and their correlation with the components of other pathways are increasing, it is important to update from time to time the available information to understand this mechanism. Furthermore, many trials have been conducted with selective medicines aimed to look for a more intelligent treatment for diseases associated with alterations in this pathway. Therefore, we review this transduction pathway to take a close look at its functioning and alterations, and to list some promising molecules for future treatments.Revisión por pare
Coró-do-milho Liogenys suturalis.
O Cerrado brasileiro possui enorme destaque no cenário agrícola nacional, tanto pela sua biodiversidade quanto pelo seu potencial para a produção de alimentos. A ocupação agrícola do Cerrado, nos últimos 30 anos, proporcionou um desenvolvimento excepcional, onde os sistemas de produção de grãos e de carne foram bastante modificados.bitstream/item/38753/1/CT200714.pdfDocumento on-line
Diagnóstico da ocorrência de pragas de solo em Mato Grosso do Sul.
bitstream/item/65250/1/30136.pdfOrganizado por: Crébio José Ávila, Rômulo Penna Scorza Júnior
Phenomenological analysis connecting proton-proton and antiproton-proton elastic scattering
Based on the behavior of the elastic scattering data, we introduce an almost
model-independent parametrization for the imaginary part of the scattering
amplitude, with the energy and momentum transfer dependences inferred on
empirical basis and selected by rigorous theorems and bounds from axiomatic
quantum field theory. The corresponding real part is analytically evaluated by
means of dispersion relations, allowing connections between particle-particle
and particle-antiparticle scattering. Simultaneous fits to proton-proton and
antiproton-proton experimental data in the forward direction and also including
data beyond the forward direction, lead to a predictive formalism in both
energy and momentum transfer. We compare our extrapolations with predictions
from some popular models and discuss the applicability of the results in the
normalization of elastic rates that can be extracted from present and future
accelerator experiments (Tevatron, RHIC and LHC).Comment: 17 pages, 17 figures, to appear in Eur. Phys. J.
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