We report on the discovery of a new extremely short period transiting extrasolar planet, WASP-19b. The planet has mass M pl = 1.15 +/- 0.08 MJ, radius R pl = 1.31 +/- 0.06 RJ, and orbital period P = ...0.7888399 +/- 0.0000008 days. Through spectroscopic analysis, we determine the host star to be a slightly super-solar metallicity (M/H = 0.1 +/- 0.1 dex) G-dwarf with T eff = 5500 +/- 100 K. In addition, we detect periodic, sinusoidal flux variations in the light curve which are used to derive a rotation period for the star of P rot = 10.5 +/- 0.2 days. The relatively short stellar rotation period suggests that either WASP-19 is somewhat young (~ 600 Myr old) or tidal interactions between the two bodies have caused the planet to spiral inward over its lifetime resulting in the spin-up of the star. Due to the detection of the rotation period, this system has the potential to place strong constraints on the stellar tidal quality factor, Q's, if a more precise age is determined.
We present the results of photometric surveys for stellar rotation in the Hyades and in Praesepe, using data obtained as part of the SuperWASP exoplanetary transit-search programme. We determined ...accurate rotation periods for more than 120 sources whose cluster membership was confirmed by common proper motion and colour-magnitude fits to the clusters' isochrones. This allowed us to determine the effect of magnetic braking on a wide range of spectral types for expected ages of ∼600 Myr for the Hyades and Praesepe. Both clusters show a tight and nearly linear relation between J−K
s colour and rotation period in the F, G and K spectral range. This confirms that loss of angular momentum was significant enough that stars with strongly different initial rotation rates have converged to the same rotation period for a given mass, by the ages of Hyades and Praesepe. In the case of the Hyades, our colour-period sequence extends well into the M dwarf regime and shows a steep increase in the scatter of the colour-period relation, with identification of numerous rapid rotators from ∼0.5 M⊙ down to the lowest masses probed by our survey (∼0.25 M⊙). This provides crucial constraints on the rotational braking time-scales and further clears the way to use gyrochronology as an accurate age measurement tool for main-sequence stars.
Aims. We have investigated the differences in apparent opening angles between the parsec-scale jets of the active galactic nuclei (AGN) detected by the Fermi Large Area Telescope during its first ...three months of operations and those of non-LAT-detected AGN. Methods. We used 15.4 GHz VLBA observations of sources from the 2 cm VLBA MOJAVE program, a subset of which comprises the statistically complete flux density limited MOJAVE sample. We determined the apparent opening angles by analyzing transverse jet profiles from the data in the image plane and by applying a model fitting technique to the data in the $(u,v)$ plane. Both methods provided comparable opening angle estimates. Results. The apparent opening angles of γ-ray bright blazars are preferentially larger than those of γ-ray weak sources. At the same time, we have found the two groups to have similar intrinsic opening angle distributions, based on a smaller subset of sources. This suggests that the jets in γ-ray bright AGN are oriented at preferentially smaller angles to the line of sight resulting in a stronger relativistic beaming. The intrinsic jet opening angle and the bulk flow Lorentz factor are found to be inversely proportional, as predicted by standard models of compact relativistic jets. If a gas dynamical jet acceleration model is assumed, the ratio of the initial pressure of the plasma in the core region P0 to the external pressure $P_{\mathrm{ext}}$ lies within the range 1.1 to 34.6, with a best fit estimate of $P_0/P_\mathrm{ext}\approx 2$.
The 'hot Jupiters' that abound in lists of known extrasolar planets are thought to have formed far from their host stars, but migrate inwards through interactions with the proto-planetary disk from ...which they were born, or by an alternative mechanism such as planet-planet scattering. The hot Jupiters closest to their parent stars, at orbital distances of only ∼0.02 astronomical units, have strong tidal interactions, and systems such as OGLE-TR-56 have been suggested as tests of tidal dissipation theory. Here we report the discovery of planet WASP-18b with an orbital period of 0.94 days and a mass of ten Jupiter masses (10 MJup), resulting in a tidal interaction an order of magnitude stronger than that of planet OGLE-TR-56b. Under the assumption that the tidal-dissipation parameter Q of the host star is of the order of 106, as measured for Solar System bodies and binary stars and as often applied to extrasolar planets, WASP-18b will be spiralling inwards on a timescale less than a thousandth that of the lifetime of its host star. Therefore either WASP-18 is in a rare, exceptionally short-lived state, or the tidal dissipation in this system (and possibly other hot-Jupiter systems) must be much weaker than in the Solar System.
We report the discovery of a transiting planet with an orbital period of 3.05 days orbiting the star TYC 7247-587-1. The star, WASP-41, is a moderately bright G8
V
V
star (
V = 11.6
V
=
11.6
) with a ...metallicity close to solar (Fe/H = -0.08 ± 0.09
Fe
/
H
=
-
0.08
±
0.09
). The star shows evidence of moderate chromospheric activity, both from emission in the cores of the Ca iiH and K ines and photometric variability with a period of 18.4 days and an amplitude of about 1%. We use a new method to show quantitatively that this periodic signal has a low false-alarm probability. The rotation period of the star implies a gyrochronological age for WASP-41 of 1.8 Gyr with an error of about 15%. We have used a combined analysis of the available photometric and spectroscopic data to derive the mass and radius of the planet (0.92 ± 0.06 M
Jup
0.92
±
0.06
M
Jup
,1.20 ± 0.06 R
Jup
1.20
±
0.06
R
Jup
). Further observations of WASP-41 can be used to explore the connections between the properties of hot Jupiter planets and the level of chromospheric activity in their host stars.
The European Association of Hematopathologists and the Society for Hematopathology have developed a new World Health Organization (WHO) classification of hematologic malignancies, including lymphoid, ...myeloid, histiocytic, and mast cell neoplasms.
Ten committees of pathologists developed lists and definitions of disease entities. A clinical advisory committee (CAC) of international hematologists and oncologists was formed to ensure that the classification would be useful to clinicians. The CAC met in November 1997 to discuss clinical issues related to the classification.
The WHO uses the Revised European-American Lymphoma (REAL) classification, published in 1994 by the International Lymphoma Study Group, to categorize lymphoid neoplasms. The REAL classification is based on the principle that a classification is a list of "real" disease entities, which are defined by a combination of morphology, immunophenotype, genetic features, and clinical features. The relative importance of each of these features varies among diseases, and there is no one gold standard. The WHO Neoplasms recognizes distinct entities defined by a combination of morphology and cytogenetic abnormalities. At the CAC meeting, which was organized around a series of clinical questions, participants reached a consensus on most of the questions posed. They concluded that clinical groupings of lymphoid neoplasms were neither necessary nor desirable. Patient treatment is determined by the specific type of lymphoma, with the addition of grade within the tumor type, if applicable, and clinical prognostic factors, such as the International Prognostic Index.
The WHO classification has produced a new and exciting degree of cooperation and communication between oncologists and pathologists from around the world, which should facilitate progress in the understanding and treatment of hematologic malignancies.
Dysregulation of the Wnt/β-catenin pathway has been observed in various malignancies, including acute myeloid leukemia (AML), where the overexpression of β-catenin is an independent adverse ...prognostic factor. β-catenin was found upregulated in the vast majority of AML samples and more frequently localized in the nucleus of leukemic stem cells compared with normal bone marrow CD34(+) cells. The knockdown of β-catenin, using a short hairpin RNA (shRNA) lentiviral approach, accelerates all-trans retinoic acid-induced differentiation and impairs the proliferation of HL60 leukemic cell line. Using in vivo quantitative tracking of these cells, we observed a reduced engraftment potential after xenotransplantation when β-catenin was silenced. However, when studying primary AML cells, despite effective downregulation of β-catenin we did not observe any impairment of their in vitro long-term maintenance on MS-5 stroma nor of their engraftment potential in vivo. Altogether, these results show that despite a frequent β-catenin upregulation in AML, leukemia-initiating cells might not be 'addicted' to this pathway and thus targeted therapy against β-catenin might not be successful in all patients.
We report the discovery of two new transiting planets from the WASP survey. WASP-42 b is a 0.500 ± 0.035 MJ planet orbiting a K1 star at a separation of 0.0548 ± 0.0017 AU with a period of ...4.9816872 ± 7.3 × 10-6 days. The radius of WASP-42 b is 1.080 ± 0.057 RJ while its equilibrium temperature is Teq = 995 ± 34 K. We detect some evidence for a small but non-zero eccentricity of e = 0.060 ± 0.013. WASP-49 b is a 0.378 ± 0.027 MJ planet around an old G6 star. It has a period of 2.7817387 ± 5.6 × 10-6 days and a separation of 0.0379 ± 0.0011 AU. This planet is slightly bloated, having a radius of 1.115 ± 0.047 RJ and an equilibrium temperature of Teq = 1369 ± 39 K. Both planets have been followed up photometrically, and in total we have obtained 5 full and one partial transit light curves of WASP-42 and 4 full and one partial light curves of WASP-49 using the Euler-Swiss, TRAPPIST and Faulkes South telescopes.
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