The low dimensional dynamical system approach in General Relativity: an example

In this paper we explore one of the most important features of the Galerkin method, which is to achieve high accuracy with a relatively modest computational effort, in the dynamics of Robinson-Trautman spacetimes.Comment: 7 pages, 5 figure

A escolha da espécie florestal na iLPF.

No sistema de integração Lavoura- Pecuária-Floresta, o componente florestal permite diversificar a produção e proporciona a melhoria na ciclagem de nutrientes, fixação de carbono e controle de erosão, além de maior conforto térmico aos animais.bitstream/item/122046/1/cpamt-2013-tonini-meneguci-folder-ilpf11-escolha-especie-floresal-ilpf.pd

B016 Impact of a 14-night intermittent hypoxia (IH) exposure on metabolic and cardiopulmonary adaptations to exercise in healthy subjects

IntroductionModifications in exercise tolerance have been reported in obstructive sleep apnea (OSA) patients. Also specific mechanisms have been speculated related to intermittent hypoxia (IH), hypertension, obesity or metabolic disturbance associated to OSA may play a significant role in exercise limitation. In order to eliminate these confounding factors we aimed to evaluate the effects of IH exposure during 14 nights in healthy subjects on exercise capacity, cardio-respiratory response and substrate oxidation during exercise.Methods12 healthy subjects (BMI: 21.8 0.5kg.m-2) were exposed to repetitive sequences of hypoxia — re-oxygenation during sleep in a hypoxic tent with appropriate cyclic re-oxygenation (rate: 30 desaturations.h-1). Maximal and sub-maximal exercise tests were performed before and after exposure in order to investigate cardiorespiratory variables and substrate oxidation parameters.ResultsIH did not modify maximal exercise parameters (VO2, heart rate, power output) nor ventilatory threshold (VTh). But this was achieved with a significant PETCO2 reduction and a VE/VCO2 increase during both maximal (Pre IH vs Post IH at VTh and Max, p<0.05) and sub-maximal (Pre vs Post at 30 % and 60 % Pmax, p<0.05) exercise tests, indicating hyperventilation. At the 1st min recovery after submaximal exercise test, diastolic arterial blood pressure (DBP) was higher after IH exposure (Pre: 60±3 vs Post: 78±2mmHg) in favour of a delayed DBP recovery following acute exercise. During sub-maximal exercise, subjects reached maximal lipid oxidation at higher power output and presented a decreased blood lactate at the same percentage of relative power after IH exposure.ConclusionExposure to 14 days of nocturnal IH is associated with an increased ventilatory response to subsequent exercise at sea level. Furthermore, delayed DBP recovery after exercise is in favor of early IH-induced cardiovascular modifications. This observation related to muscular exercise adaptations confirms the efficacy of the model in reproducing early cardiovascular alterations occurring in OSAS. Moreover, this model induces metabolic adaptations as soon as 14 nights of exposure

Angular Momentum Transfer in Dark Matter Halos: Erasing the Cusp

We propose that angular momentum transfer from the baryons to the Dark Matter (DM) during the early stages of galaxy formation can flatten the halo inner density profile and modify the halo dynamics. We compute the phase-space distribution function of DM halos, that corresponds to the density and anisotropy profiles obtained from N-body simulations in the concordance cosmology. We then describe an injection of angular momentum into the halo by modifying the distribution function, and show that the system evolves into a new equilibrium configuration; the latter features a constant central density and a tangentially-dominated anisotropy profile in the inner regions, while the structure is nearly unchanged beyond 10% of the virial radius. Then we propose a toy model to account for such a halo evolution, based on the angular momentum exchange due to dynamical friction; at the epoch of galaxy formation this is efficiently exerted by the DM onto the gas clouds spiralling down the potential well. The comparison between the angular momentum profile gained by the halo through dynamical friction and that provided by the perturbed distribution function reveals a surprising similarity, hinting at the reliability of the process.Comment: 10 pages, 6 figures. Minor changes, ApJ accepte

Biomass allocation in Eucalyptus in monoculture and silvipastoral system.

Resumo. Título em inglês e conteúdo em português

Biomass and leaf area in Eucalyptus clones in crop-livestock-forestry systems: implications for pruning.

Resumo

Atualizações em calagem de solos em Rondônia.

Este artigo trata da degradação química dos solos e apresenta métodos de recomendação de calagem.Editado por: Paulo Guilherme Salvador Wadt; Alaerto Luiz Marcolan; Stella Cristiani Gonçalves Matoso e Marcos Gervasio Pereira

Prolapso de uretra em cão da raça maltês. Relato de caso

O artigo não apresenta resumo

Observational Manifestations of the First Protogalaxies in the 21 cm Line

The absorption properties of the first low-mass protogalaxies (mini-halos) forming at high redshifts in the 21-cm line of atomic hydrogen are considered. The absorption properties of these protogalaxies are shown to depend strongly on both their mass and evolutionary status. The optical depths in the line reach $\sim$0.1-0.2 for small impact parameters of the line of sight. When a protogalaxy being compressed, the influence of gas accretion can be seen manifested in a non-monotonic frequency dependence of the optical depth. The absorption characteristics in the 21-cm line are determined by the thermal and dynamical evolution of the gas in protogalaxies. Since the theoretical line width in the observer's reference frame is 1-6 kHz and the expected separation between lines 8.4 kHz, the lines from low mass protogalaxies can be resolved using ongoing and future low frequency interferometers.Comment: 12 pages, 5 figure