1,269 research outputs found
Effets de la pauvreté, la vulnérabilité biologique et la vulnérabilité psychosociale pendant la petite enfance pour les crises d'asthme à 7 ans dans la cohorte ÉLDEQ
Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal
Long-distance structure of the X(3872)
We investigate heavy quark symmetries for heavy meson hadronic molecules, and
explore the consequences of assuming the X(3872) and as an
isoscalar and an isovector hadronic molecules,
respectively. The symmetry allows to predict new hadronic molecules, in
particular we find an isoscalar bound state with a mass
about 10580 MeV and the isovector charmonium partners of the and
the states. Next, we study the
three body decay. This decay mode is more sensitive to the long-distance
structure of the X(3872) resonance than its and
decays, which are mainly controlled by the short distance part of the X(3872)
molecular wave function. We discuss the final state
interactions, which in some situations become quite important. Indeed in these
cases, a precise measurement of this partial decay width could provide precise
information on the interaction strength between the charm
mesons.Comment: Talk presented at the "XI International Conference on Hyperons, Charm
and Beauty Hadrons (BEACH 2014)", Birmingham (U.K.), July 201
Renormalization of NN-Scattering with One Pion Exchange and Boundary Conditions
A non perturbative renormalization scheme for Nucleon-Nucleon interaction
based on boundary conditions at short distances is presented and applied to the
One Pion Exchange Potential. It is free of off-shell ambiguities and
ultraviolet divergences, provides finite results at any step of the calculation
and allows to remove the short distance cut-off in a suitable way. Low energy
constants and their non-perturbative evolution can directly be obtained from
experimental threshold parameters in a completely unique and model independent
way when the long range explicit pion effects are eliminated. This allows to
compute scattering phase shifts which are, by construction consistent with the
effective range expansion to a given order in the C.M. momentum . In the
singlet and triplet channels ultraviolet fixed points
and limit cycles are obtained respectively for the threshold parameters. Data
are described satisfactorily up to CM momenta of about .Comment: 22 pages, 10 figures, revte
A theory for the low-energy optical sum-rule in moir\'e graphene
Few layers of graphene at small twist-angles have emerged as a fascinating
platform for studying the problem of strong interactions in regimes with a
nearly quenched single-particle kinetic energy and non-trivial band topology.
Starting from the strong-coupling limit of twisted bilayer graphene with a
vanishing single-electron bandwidth and interlayer-tunneling between the same
sublattice sites, we present an analytical theory of the Coulomb
interaction-induced low-energy optical spectral weight at all
fillings. In this limit, while the interaction-induced single-particle
dispersion is finite, the optical spectral weight vanishes identically at
integer fillings. We study corrections to the optical spectral weight by
systematically including the effects of experimentally relevant strain-induced
renormalization of the single-electron bandwidth and interlayer tunnelings
between the same sublattice sites. Given the relationship between the optical
spectral weight and the diamagnetic response that controls superconducting
, our results highlight the relative importance of specific parent
insulating phases in enhancing the tendency towards superconductivity when
doped away from integer fillings.Comment: Main text: 9 pages, 2 figures, Supplementary information: 10 page
La EconomÃa PolÃtica del Proceso Presupuestario: El caso peruano
Este estudio presenta el caso del Perú. El documento brinda una descripción de los actores principales involucrados en el proceso presupuestario y de sus interacciones. Describe los principales determinantes polÃticos y económicos del desempeño fiscal y considera el impacto de los arreglos polÃticos e institucionales que gobiernan el funcionamiento del proceso presupuestario en sus diferentes etapas.
Recursive Detection and Analysis of Nanoparticles in Scanning Electron Microscopy Images
In this study, we present a computational framework tailored for the precise
detection and comprehensive analysis of nanoparticles within scanning electron
microscopy (SEM) images. The primary objective of this framework revolves
around the accurate localization of nanoparticle coordinates, accompanied by
secondary objectives encompassing the extraction of pertinent morphological
attributes including area, orientation, brightness, and length.
Constructed leveraging the robust image processing capabilities of Python,
particularly harnessing libraries such as OpenCV, SciPy, and Scikit-Image, the
framework employs an amalgamation of techniques, including thresholding,
dilating, and eroding, to enhance the fidelity of image processing outcomes.
The ensuing nanoparticle data is seamlessly integrated into the RStudio
environment to facilitate meticulous post-processing analysis. This encompasses
a comprehensive evaluation of model accuracy, discernment of feature
distribution patterns, and the identification of intricate particle
arrangements. The finalized framework exhibits high nanoparticle identification
within the primary sample image and boasts 97\% accuracy in detecting particles
across five distinct test images drawn from a SEM nanoparticle dataset.
Furthermore, the framework demonstrates the capability to discern nanoparticles
of faint intensity, eluding manual labeling within the control group.Comment: 9 pages, 10 figure
Unidirectional Neuronal Cell growth and Differentiation on Aligned Polyhydroxyalkanoate Blend Microfibres with Varying Diameters
Polyhydroxyalkanoates (PHAs) are a family of prokaryotic-derived biodegradable and biocompatible natural polymers known to exhibit neuroregenerative properties. In this work, poly(3-hydroxybutyrate), P(3HB) and poly(3-hydroxyoctanoate), P(3HO), have been combined to form blend fibres for directional guidance of neuronal cell growth and differentiation. A 25:75 P(3HO)/P(3HB) blend (PHA blend) was used for the manufacturing of electrospun fibres as resorbable scaffolds to be used as internal guidance lumen structures in nerve conduits. The biocompatibility of these fibres was studied using neuronal and Schwann cells. Highly aligned and uniform fibres with varying diameters were fabricated by controlling electrospinning parameters. The resulting fibre diameters were 2.4 ± 0.3 µm, 3.7 ± 0.3 µm and 13.5 ± 2.3 µm for small, medium and large diameter fibres respectively. The cell response to these electrospun fibres was investigated with respect to growth and differentiation. Cell migration observed on the electrospun fibres showed topographical guidance in accordance with the direction of the fibres. The correlation between fibre diameter and neuronal growth under two conditions; individually and in co-culture with Schwann cells was evaluated. Results obtained from both assays revealed that all PHA blend fibre groups were able to support growth and guide aligned distribution of neuronal cells and there was a direct correlation between the fibre diameter and neuronal growth and differentiation. This work has led to the development of a family of unique biodegradable and highly biocompatible 3D substrates capable of guiding and facilitating the growth, proliferation and differentiation of neuronal cells as internal structures within nerve conduits
Intermediate-scale theory for electrons coupled to frustrated local-moments
A classic route for destroying long-lived electronic quasiparticles in a
weakly interacting Fermi liquid is to couple them to other low-energy degrees
of freedom that effectively act as a bath. We consider here the problem of
electrons scattering off the spin fluctuations of a geometrically frustrated
antiferromagnet, whose non-linear Landau-Lifshitz dynamics, which remains
non-trivial at all temperatures, we model in detail. At intermediate
temperatures and in the absence of any magnetic ordering, the fluctuating
local-moments lead to a non-trivial angular anisotropy of the scattering-rate
along the Fermi surface, which disappears with increasing temperature,
elucidating the role of "hot-spots". Over a remarkably broad window of
intermediate and high temperatures, the electronic properties can be described
by employing a local approximation for the dynamical spin-response. This we
contrast with the more familiar setup of electrons scattering off classical
phonons, whose high-temperature limit differs fundamentally on account of their
unbounded Hilbert space. We place our results in the context of layered
magnetic delafossite compounds.Comment: 4.5 pages, 3 figures. Supplementary material: 6 pages, 4 figure
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