Universal theory of nonlinear Luttinger liquids

One-dimensional quantum fluids are conventionally described by using an effective hydrodynamic approach known as Luttinger liquid theory. As the principal simplification, a generic spectrum of the constituent particles is replaced by a linear one, which leads to a linear hydrodynamic theory. We show that to describe the measurable dynamic response functions one needs to take into account the nonlinearity of the generic spectrum and thus of the resulting quantum hydrodynamic theory. This nonlinearity leads, for example, to a qualitative change in the behavior of the spectral function. The universal theory developed in this article is applicable to a wide class of one-dimensional fermionic, bosonic, and spin systems.Comment: final published version with supporting online materia

Cultivo do milheto.

bitstream/item/35595/1/Cultivo-milheto.pd

Effect of stent position on flow characteristics in a cerebral aneurysm

The position of an intracranial stent in relation to the ostium of a cerebral aneurysm can significantly affect the blood flow characteristics through the ostium and inside the aneurysm. An idealised cerebral artery and aneurysm were simulated with a pulsatile flow. Simulation results show that the effect on mass inflow between two stent positions is about 20% whereas the difference in the porosity effect of the pattern at these two positions is around 3%. The remainder may be attributed to differences in flow velocity profile across the stent into the aneurysm. The implications for clinical practice are an important consideration as the surgeon may place the stent in any position between the two investigated and hence this will lead to markedly different stent performance. Therefore, computational tools that take into account the variability of stent placement will be valuable for assisting surgical planning

Ground-state configurations in ferromagnetic nanotori

Magnetization ground states are studied in toroidal nanomagnets. The energetics associated to the ferromagnetic, vortex and onion-like configurations are explicitly computed. The analysis reveals that the vortex appears to be the most prominent of such states, minimizing total energy in every torus with internal radius $r\gtrsim10\,{\rm nm}$ (for Permalloy). For $r\lesssim10\,{\rm nm}$ the vortex remains the most favorable pattern whenever $R/\ell_{ex}\gtrsim1.5$ ($R$ is the torus external radius and $\ell_{ex}$ is the exchange length), being substituted by the ferromagnetic state whenever $R/\ell_{ex}\lesssim1.5$.Comment: 16 pages, 9 figures, 3 apendices, Revtex forma

Líquenes epífitos: una herramienta para estudiar la continuidad ecológica en Isla Mocha, Chile

The purpose of this work was to study the ecological continuity Mocha Island National Reserve, through the knowledge of the richness and frequency of epiphytic lichens in 14 plots distributed at random within the reserve. The tree biomass and upper-stem volume were quantified for to establish correlations that may explain the distribution of epiphytic lichens. It proposes a new index of ecological continuity with cyanolichens (ICEC) for to establish the degree of alteration of this natural ecosystem. The total richness of lichenized fungi was 33 species, 3 of which are new records for Chile: Fissurina triticea; Pyrenula neglecta and Stick, subcaperata. A statistically significant relationship was founded between cyanolichens and upper-stem volume, which could indicate preference of this type of lichens by forest ecosystem with a large upper-stem volume. In basis of the ICEC proposed in this work, Mocha Island National Reserve is defined as an altered ecosystem