33 research outputs found
Interferometric Space Missions for the Search for Terrestrial Exoplanets: Requirements on the Rejection Ratio
The requirements on space missions designed to study Terrestrial exoplanets
are discussed. We then investigate whether the design of such a mission,
specifically the Darwin nulling interferometer, can be carried out in a
simplified scenario. The key element here is accepting somewhat higher levels
of stellar leakage. We establish detailed requirements resulting from the
scientific rationale for the mission, and calculate detailed parameters for the
stellar suppression required to achieve those requirements. We do this
utilizing the Darwin input catalogue. The dominating noise source for most
targets in this sample is essentially constant for all targets, while the
leakage diminishes with the square of the distance. This means that the stellar
leakage has an effect on the integration time only for the nearby stars, while
for the more distant targets its influence decreases significantly. We assess
the impact of different array configurations and nulling profiles and identify
the stars for which the detection efficiency can be maximized.Comment: 21 pages, 8 figures; TBP in Astrophysics and Space Science 200
Transcriptional repression of NFKBIA triggers constitutive IKK- and proteasome-independent p65/RelA activation in senescence
The IκB kinase (IKK)‐NF‐κB pathway is activated as part of the DNA damage response and controls both inflammation and resistance to apoptosis. How these distinct functions are achieved remained unknown. We demonstrate here that DNA double‐strand breaks elicit two subsequent phases of NF‐κB activation in vivo and in vitro, which are mechanistically and functionally distinct. RNA‐sequencing reveals that the first‐phase controls anti‐apoptotic gene expression, while the second drives expression of senescence‐associated secretory phenotype (SASP) genes. The rapidly activated first phase is driven by the ATM‐PARP1‐TRAF6‐IKK cascade, which triggers proteasomal destruction of inhibitory IκBα, and is terminated through IκBα re‐expression from the NFKBIA gene. The second phase, which is activated days later in senescent cells, is on the other hand independent of IKK and the proteasome. An altered phosphorylation status of NF‐κB family member p65/RelA, in part mediated by GSK3β, results in transcriptional silencing of NFKBIA and IKK‐independent, constitutive activation of NF‐κB in senescence. Collectively, our study reveals a novel physiological mechanism of NF‐κB activation with important implications for genotoxic cancer treatment
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
Diversidade genética por marcadores moleculares em Fusarium oxysporum f. sp. cubense no Estado de Santa Catarina
Arbeitslosigkeit und Stellenannahmebereitschaft: Erste Ergebnisse eines Faktoriellen Survey Moduls
Modeling and Testing of Web Based Systems
International audienceThe success and the massive adoption of Web applications and services are pushing the community to increase and enhance their developments. By that way, the complexity and size of Web-based systems are definitely growing. Accordingly, the need for sophisticated and complete methods used to test the reliability and security aspects of Web systems is increasing as well. Quality and relevant test cases development can achieve up to 70% of the total cost of the project when these test cases are hand crafted. Because of this, the industry and the research community are making big efforts to automate test cases generation. That is the reason why the test generator must be supplied with a precise and unambiguous semantic description of the implementation under test (IUT), i.e. a formal model. This chapter presents two methodologies to attain automatic test cases generation: The first one applies extended finite state machines to model Web services composition described in WS-BPEL, while the other one uses UML to model Web applications. Together with the formal models of the web systems, this chapter presents methods for conformance and non-regression test generation