12,401 research outputs found
On Quantum Special Kaehler Geometry
We compute the effective black hole potential V of the most general N=2, d=4
(local) special Kaehler geometry with quantum perturbative corrections,
consistent with axion-shift Peccei-Quinn symmetry and with cubic leading order
behavior. We determine the charge configurations supporting axion-free
attractors, and explain the differences among various configurations in
relations to the presence of ``flat'' directions of V at its critical points.
Furthermore, we elucidate the role of the sectional curvature at the
non-supersymmetric critical points of V, and compute the Riemann tensor (and
related quantities), as well as the so-called E-tensor. The latter expresses
the non-symmetricity of the considered quantum perturbative special Kaehler
geometry.Comment: 1+43 pages; v2: typo corrected in the curvature of Jordan symmetric
sequence at page 2
Localization properties of a tight-binding electronic model on the Apollonian network
An investigation on the properties of electronic states of a tight-binding
Hamiltonian on the Apollonian network is presented. This structure, which is
defined based on the Apollonian packing problem, has been explored both as a
complex network, and as a substrate, on the top of which physical models can
defined. The Schrodinger equation of the model, which includes only nearest
neighbor interactions, is written in a matrix formulation. In the uniform case,
the resulting Hamiltonian is proportional to the adjacency matrix of the
Apollonian network. The characterization of the electronic eigenstates is based
on the properties of the spectrum, which is characterized by a very large
degeneracy. The rotation symmetry of the network and large number of
equivalent sites are reflected in all eigenstates, which are classified
according to their parity. Extended and localized states are identified by
evaluating the participation rate. Results for other two non-uniform models on
the Apollonian network are also presented. In one case, interaction is
considered to be dependent of the node degree, while in the other one, random
on-site energies are considered.Comment: 7pages, 7 figure
Ante‐natal and post‐natal influences on neonatal immunity, growth and puberty of calves—a review
Calf immunity, growth and puberty are important factors affecting heifer productivity. The first four weeks of age are critical for reducing calf morbidity and mortality. It is well documented that colostrum is paramount to neonatal nutrition and passive immunity, however, adap-tation to extra‐uterine life starts early during embryonic development. Therefore, successful calf rearing strategies are underpinned by adequate maternal nutrition during gestation, and good co-lostrum management. A deeper understanding of these interactions paves the way for developing strategies to improve immune responses to environmental pathogens, optimal growth and timely attainment of puberty in calves. The literature reviewed here shows that there are opportunities to enhance the future performance of cattle paying attention to the interaction of nutrition and immunity at each developmental stage. Therefore, the objective of this review is to give the reader an overview of interactions between immunity, growth and puberty in dairy calves and highlight how these influence future performances
“Colorir para agir”: educar pela arte, para a paz
O projeto “Colorir para agir” foi concebido e implementado com o objetivo de alertar para a problemática crescente da violência escolar e contribuir para a prevenção e diminuição das práticas agressivas de crianças em idade escolar, procurando valorizar a convivência harmoniosa entre pares. Aliando a educação não formal às artes, este programa de intervenção desenvolveu um conjunto de atividades no âmbito das artes plásticas, abrangendo 21 crianças, com idades compreendidas entre os 6 e os 13 anos de um Agrupamento de Escolas de Valongo do Vouga, no concelho de Águeda (Portugal). Estas culminaram na realização de um mural gigante pintado na parede exterior da instituição, que ficou como símbolo da não violência escolar e da educação para a paz
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