28 research outputs found
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
First report of Lecanodiaspis dendrobii Douglas, 1892 (Hemiptera: Lecanodiaspididae) and the associated parasitoid Cephaleta sp. (Hymenoptera: Pteromalidae) in Brazil
The Theory of Brown Dwarfs and Extrasolar Giant Planets
Straddling the traditional realms of the planets and the stars, objects below
the edge of the main sequence have such unique properties, and are being
discovered in such quantities, that one can rightly claim that a new field at
the interface of planetary science and and astronomy is being born. In this
review, we explore the essential elements of the theory of brown dwarfs and
giant planets, as well as of the new spectroscopic classes L and T. To this
end, we describe their evolution, spectra, atmospheric compositions, chemistry,
physics, and nuclear phases and explain the basic systematics of
substellar-mass objects across three orders of magnitude in both mass and age
and a factor of 30 in effective temperature. Moreover, we discuss the
distinctive features of those extrasolar giant planets that are irradiated by a
central primary, in particular their reflection spectra, albedos, and transits.
Aspects of the latest theory of Jupiter and Saturn are also presented.
Throughout, we highlight the effects of condensates, clouds, molecular
abundances, and molecular/atomic opacities in brown dwarf and giant planet
atmospheres and summarize the resulting spectral diagnostics. Where possible,
the theory is put in its current observational context.Comment: 67 pages (including 36 figures), RMP RevTeX LaTeX, accepted for
publication in the Reviews of Modern Physics. 30 figures are color. Most of
the figures are in GIF format to reduce the overall size. The full version
with figures can also be found at:
http://jupiter.as.arizona.edu/~burrows/papers/rm
Activating mutations in the KCNJ11 gene encoding the ATP-sensitive potassium channel subunit Kir6.2 are associated with a spectrum of early-onset syndromic and non-syndromic diabetes
Propriedades biomecĂąnicas da fĂĄscia lata e do ligamento cruzado cranial de cĂŁes Biomechanical properties of canine fascia lata and cranial cruciate ligament
PreparaçÔes bilaterais do ligamento cruzado cranial e da fĂĄscia lata de 15 cĂŁes foram testadas na mĂĄquina Instron, modelo 4482. Os animais, de ambos os sexos, idade entre um e quatro anos, pesavam em mĂ©dia 11,80 ± 1,99kg. Os retalhos de fĂĄscia lata foram testados retilĂneos e torcidos e o ligamento cruzado cranial foi testado mantendo um Ăąngulo de 135° entre a tĂbia e o fĂȘmur e 0°, 15° de rotação externa e 15° de rotação interna da tĂbia em relação ao fĂȘmur. A velocidade dos testes de tração foi de 8,47mm por segundo. A força mĂĄxima dos retalhos de fĂĄscia lata foi aproximadamente de 290 Newtons, e a tensĂŁo mĂĄxima, 28 Megapascal. A torção nĂŁo influenciou na resistĂȘncia dos retalhos de fĂĄscia lata. A rotação externa e interna da tĂbia de 15Âș tambĂ©m nĂŁo influenciou na força mĂĄxima do ligamento cruzado cranial, que foi aproximadamente de 660 Newtons, nem na tensĂŁo mĂĄxima, que foi cerca de 75 Megapascal. Os retalhos de fĂĄscia lata apresentaram 44% da força mĂĄxima e 37% da tensĂŁo mĂĄxima do ligamento, no entanto, os retalhos torcidos mostraram maior deformação do que os retalhos retilĂneos, alcançando cerca de 70% da deformação do ligamento, sendo essa forma a mais indicada na substituição do ligamento cruzado cranial.<br>Bilateral preparations of fascia lata and cranial cruciate ligament from 15 dogs were tested in Instron machine, model 4482. Dogs were from both sexes, between one and four years of age and weighing in average about 11.80 ± 1.99kg. Fascia lata strips were tested straight and twisted and the cranial cruciate ligaments were tested with an angle of 135° between the femur and tibia and 0°, 15° of external tibial rotation and 15° of internal tibial rotation in relation to femur. The traction test velocity was 8.47mm per second. The maximum force of fascia lata strips was of approximately 290 Newtons and the maximum stress, 28 Megapascal. Similar results of strength and stress properties were found for the strips of fascia lata straight and twisted, although twisted strips presented a higher deformation than straight ones. External and internal tibial rotation did not influence the maximum force and maximum stress of the cranial cruciate ligament, that were of about 660 Newtons and 75 Megapascal, respectively. Fascia lata strips reached 44% of ligaments maximum force and 37% of maximum strain, and twisted strips reached 70% of ligaments maximum deformation, deserving straight strips to be recommended for cranial cruciate ligament substitution in dogs