Hamiltonian dynamics for Einstein's action in G→\rightarrow0 limit

The Hamiltonian analysis for the Einstein's action in $G\to 0$ limit is performed. Considering the original configuration space without involve the usual $ADM$ variables we show that the version $Gto 0$ for Einstein's action is devoid of physical degrees of freedom. In addition, we will identify the relevant symmetries of the theory such as the extended action, the extended Hamiltonian, the gauge transformations and the algebra of the constraints. As complement part of this work, we develop the covariant canonical formalism where will be constructed a closed and gauge invariant symplectic form. In particular, using the geometric form we will obtain by means of other way the same symmetries that we found using the Hamiltonian analysis

Descrição da larva de Amblyomma romitii Tonelli-Rondelli, 1939(ACARI: IXODIDAE) por microscopia eletrônica de varredura.

Este trabalho teve por objetivo descrever a larva de Amblyomma romitii com base em microscopia eletrônica de varredura

Noise Sources in Photometry and Radial Velocities

The quest for Earth-like, extrasolar planets (exoplanets), especially those located inside the habitable zone of their host stars, requires techniques sensitive enough to detect the faint signals produced by those planets. The radial velocity (RV) and photometric transit methods are the most widely used and also the most efficient methods for detecting and characterizing exoplanets. However, presence of astrophysical "noise" makes it difficult to detect and accurately characterize exoplanets. It is important to note that the amplitude of such astrophysical noise is larger than both the signal of Earth-like exoplanets and state-of-the-art instrumentation limit precision, making this a pressing topic that needs to be addressed. In this chapter, I present a general review of the main sources of noise in photometric and RV observations, namely, stellar oscillations, granulation, and magnetic activity. Moreover, for each noise source I discuss the techniques and observational strategies which allow us to mitigate their impact.Comment: 11 pages, 2 tables, Lecture presented at the IVth Azores International Advanced School in Space Sciences on "Asteroseismology and Exoplanets: Listening to the Stars and Searching for New Worlds" (arXiv:1709.00645), which took place in Horta, Azores Islands, Portugal in July 201

An assessment of composite repair system in offshore platform for corroded circumferential welds in super duplex steel pipe

The main aim of this study is to assess the effectiveness of a composite repair system in severely corroded circumferential welds in super duplex stainless steel pipes as a preventive measure against the premature corrosion damage at the welds. Artificial defects were fabricated on the super duplex steel tube in order to reproduce the localized corrosion damage defects found in real welded joints. Three kinds of through thickness defects were considered: 25%, 50% and 96% of the perimeter of the pipe. The performance of the repaired pipe was assessed by hydrostatic tests as per ISO 24817 standard. The results showed that the composite repair system can sustain the designed failure pressure even for the pipe damaged with through-wall defect up to 96% of the perimeter of the pipe. Hence, the composite repair system can be used as a preliminary tool to protect the unexpected or premature failure at the welds and maintain an adequate level of mechanical strength for a given operating pressure. This composite repair system can assure that the pipe will not leak until a planned maintenance of the line. Nevertheless, further work is still desirable to improve the confidence in the long-term performance of bonded composite