94 research outputs found
A super-Earth-sized planet orbiting in or near the habitable zone around Sun-like star
We present the discovery of a super-earth-sized planet in or near the
habitable zone of a sun-like star. The host is Kepler-69, a 13.7 mag G4V-type
star. We detect two periodic sets of transit signals in the three-year flux
time series of Kepler-69, obtained with the Kepler spacecraft. Using the very
high precision Kepler photometry, and follow-up observations, our confidence
that these signals represent planetary transits is >99.1%. The inner planet,
Kepler-69b, has a radius of 2.24+/-0.4 Rearth and orbits the host star every
13.7 days. The outer planet, Kepler-69c, is a super-Earth-size object with a
radius of 1.7+/-0.3 Rearth and an orbital period of 242.5 days. Assuming an
Earth-like Bond albedo, Kepler-69c has an equilibrium temperature of 299 +/- 19
K, which places the planet close to the habitable zone around the host star.
This is the smallest planet found by Kepler to be orbiting in or near habitable
zone of a Sun-like star and represents an important step on the path to finding
the first true Earth analog.Comment: Accepted for publication in the Astrophysical Journa
Incerteza, investimento e política monetária : a alternativa de Keynes e da escola pós-Keynesiana
Orientador: Fernando Motta CorreiaMonografia(Graduação) - Universidade Federal do Paraná,Setor de Ciências Sociais Aplicadas, Curso de Ciências EconômicasResumo: A teoria econômica (neo-)clássica dominou o pensamento econômico, acadêmico e
prático, por um século, até a grande depressão de 1929. É neste contexto que
Keynes publica sua principal obra: A Teoria Geral do Juro, do Emprego e da Moeda
na qual ele deu ênfase ao termo geral pois os postulados (neo-) clássicos
aplicavam-se somente no limite das possíveis situações de equilíbrio, o que não a
era realidade da conjuntura econômica da época. A teoria keynesiana rompe
radicalmente com a teoria (neo-) clássica nos trazendo uma nova visão de mundo,
denominada por Keynes inicialmente de economia monetária. A teoria de Keynes
sobre a determinação do investimento é de fundamental importância para o
entendimento deste novo conceito, a qual nega todos os axiomas (neo-) clássicos
sobre o tema e serve de pilar para o arcabouço teórico dos verdadeiros seguidores
de Keynes, conhecidos como pós-keynesianos, os quais, ampliariam o conceito de
economia monetária para economia monetária de produção, visão de mundo
fundamental para provar que a política monetária discricionária é eficaz em
aumentar o emprego, a renda e, consequentemente, o produto, diferentemente da
visão das escolas monetarista e novo-clássicaAbstract: The (new-) classical theory dominated the economic thought, academically and
practically for over one hundred years until the great depression of 1929. In this
context Keynes publishes his most important work: The General Theory of
Employment, Interest and Money, which he gave emphasis to the term general
because the (new-) classical postulates worked only to explain an extremely limited
situation, which was not the conjuncture reality of that time. The keynesian theory
denies completely the (new-) classical arguments, giving us, a new way to
understand how the economy works, denominated by Keynes of Monetary Economy.
His theory of how the investment is determined is extremely important for the
comprehension of this new concept, which, denies all (new-) classical postulates
about the theme and is mostly important for the theoretical development of the real
Keynes followers, also known as post-keynesian economists, which, were
responsible for developing the concept of Monetary Economy into Monetary
Economy of Production, which is fundamental to prove that discretionary monetarypolicy
is capable of raising employment, income and consequently the product of the
economy, completely different, than the thoughts of the monetarist and new- classical
school of economics because according to them the monetary policy would not be
efficient increasing employment, income and, last but not least, the produc
Validation of Kepler's Multiple Planet Candidates. III: Light Curve Analysis & Announcement of Hundreds of New Multi-planet Systems
The Kepler mission has discovered over 2500 exoplanet candidates in the first
two years of spacecraft data, with approximately 40% of them in candidate
multi-planet systems. The high rate of multiplicity combined with the low rate
of identified false-positives indicates that the multiplanet systems contain
very few false-positive signals due to other systems not gravitationally bound
to the target star (Lissauer, J. J., et al., 2012, ApJ 750, 131). False
positives in the multi- planet systems are identified and removed, leaving
behind a residual population of candidate multi-planet transiting systems
expected to have a false-positive rate less than 1%. We present a sample of 340
planetary systems that contain 851 planets that are validated to substantially
better than the 99% confidence level; the vast majority of these have not been
previously verified as planets. We expect ~2 unidentified false-positives
making our sample of planet very reliable. We present fundamental planetary
properties of our sample based on a comprehensive analysis of Kepler light
curves and ground-based spectroscopy and high-resolution imaging. Since we do
not require spectroscopy or high-resolution imaging for validation, some of our
derived parameters for a planetary system may be systematically incorrect due
to dilution from light due to additional stars in the photometric aperture.
None the less, our result nearly doubles the number of verified exoplanets.Comment: 138 pages, 8 Figures, 5 Tables. Accepted for publications in the
Astrophysical Journa
Masses, radii, and orbits of small Kepler planets : The transition from gaseous to rocky planets
We report on the masses, sizes, and orbits of the planets orbiting 22 Kepler stars. There are 49 planet candidates around these stars, including 42 detected through transits and 7 revealed by precise Doppler measurements of the host stars. Based on an analysis of the Kepler brightness measurements, along with high-resolution imaging and spectroscopy, Doppler spectroscopy, and (for 11 stars) asteroseismology, we establish low false-positive probabilities (FPPs) for all of the transiting planets (41 of 42 have an FPP under 1%), and we constrain their sizes and masses. Most of the transiting planets are smaller than three times the size of Earth. For 16 planets, the Doppler signal was securely detected, providing a direct measurement of the planet's mass. For the other 26 planets we provide either marginal mass measurements or upper limits to their masses and densities; in many cases we can rule out a rocky composition. We identify six planets with densities above 5 g cm-3, suggesting a mostly rocky interior for them. Indeed, the only planets that are compatible with a purely rocky composition are smaller than 2 R ⊕. Larger planets evidently contain a larger fraction of low-density material (H, He, and H2O).Peer reviewedFinal Accepted Versio
A sub-Mercury-sized exoplanet
Since the discovery of the first exoplanet we have known that other planetary
systems can look quite unlike our own. However, until recently we have only
been able to probe the upper range of the planet size distribution. The high
precision of the Kepler space telescope has allowed us to detect planets that
are the size of Earth and somewhat smaller, but no previous planets have been
found that are smaller than those we see in our own Solar System. Here we
report the discovery of a planet significantly smaller than Mercury. This tiny
planet is the innermost of three planets that orbit the Sun-like host star,
which we have designated Kepler-37. Owing to its extremely small size, similar
to that of Earth's Moon, and highly irradiated surface, Kepler-37b is probably
a rocky planet with no atmosphere or water, similar to Mercury.Comment: Accepted and published in Nature (2013 Feb 28). This is the submitted
version of paper, merged with the Supplementary Informatio
The HD 191939 Exoplanet System is Well-Aligned and Flat
We report the sky-projected spin-orbit angle for HD 191939 b, the innermost planet in a 6 planet system, using Keck/KPF to detect the Rossiter-McLaughlin (RM) effect. Planet b is a sub-Neptune with radius 3.4 0.8 R and mass 10.0 0.7 M with an RM amplitude 1 ms. We find the planet is consistent with a well-aligned orbit, measuring 3.7 5.0 degrees. Additionally, we place new constraints on the mass and period of the distant super-Jupiter, planet f, finding it to be 2.88 0.26 on a 2898 152 day orbit. With these new orbital parameters, we perform a dynamical analysis of the system and constrain the mutual inclination of the non-transiting planet e to be smaller than 12 degrees relative to the plane shared by the inner three transiting planets. Additionally, the further planet f is inclined off this shared plane, the greater the amplitude of precession for the entire inner system, making it increasingly unlikely to measure an aligned orbit for planet b. Through this analysis, we show that this system\u27s wide variety of planets are all well-aligned with the star and nearly co-planar, suggesting that the system formed dynamically cold and flat out of a well-aligned proto-planetary disk, similar to our own solar system.11 pages, 4 figures, Accepted for publication in The Astronomical Journa
Two-year follow-up of Helicobacter pylori infection in C57BL/6 and Balb/cA mice
Helicobacter pylori infection is associated with chronic gastritis, peptic ulcer disease, gastric adenocarcinoma and MALT lymphoma. We previously found high-grade lymphoma after 13 months' H. pylori infection in C57BL/6 mice. In this study we followed H. pylori infection by three different isolates in C57BL/6 and Balb/cA mice for 23 months. Six-week-old C57BL/6 and Balb/cA mice were infected with H. pylori strains 119p (CagA+, VacA+), SS1 (CagA+, VacA+) and G50 (CagA-, VacA-). Mice were followed at 2 weeks, 10 weeks and 23 months post-inoculation (p.i.) by culture, histopathology and serology. Strain G50 was only reisolated from mice 2 weeks p.i. There was no difference in colonization between strain 119p and SS1 at 10 weeks p.i., whereas SS1 gave 100% colonization versus 119p gave 50% 23 months p.i.. Interestingly, the inflammation score was higher in mice infected with strain 119p than with SS1 10-week p.i., and there were lymphoepithelial lesions in mice infected with strain 119p and G50 but not with SS1 at 23 months post-infection. Eight mice infected with strains 119p and G50 developed gastric lymphoma (grade 5 and 4). One C57BL/6 mouse infected with strain 119p developed hepatocellular carcinoma after 23 months. Immunoblot showed specific bands of 2633 kDa against H. pylori in infected mice, and two mice infected with strain SSI reacted with antibodies to the 120 kDa CagA toxin. Conclusion: A reproducible animal model for H. pylori-induced lymphoma and possibly hepatocellular carcinoma is described. Strain diversity may lead to different outcomes of H. pylori infection
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