603 research outputs found
Restoration of Hypoglycemia Awareness After Islet Transplantation
OBJECTIVE—To determine the impact of islet transplantation (ITx) on hypoglycemia awareness in patients with unstable type 1 diabetes and its relation to islet function
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Low Susceptibility of Invasive Red Lionfish (Pterois volitans) to a Generalist Ectoparasite in Both Its Introduced and Native Ranges
Escape from parasites in their native range is one of many mechanisms that can contribute to the success of an invasive
species. Gnathiid isopods are blood-feeding ectoparasites that infest a wide range of fish hosts, mostly in coral reef habitats.
They are ecologically similar to terrestrial ticks, with the ability to transmit blood-borne parasites and cause damage or even
death to heavily infected hosts. Therefore, being highly resistant or highly susceptible to gnathiids can have significant
fitness consequences for reef-associated fishes. Indo-Pacific red lionfish (Pterois volitans) have invaded coastal habitats of the
western tropical and subtropical Atlantic and Caribbean regions. We assessed the susceptibility of red lionfish to parasitic
gnathiid isopods in both their native Pacific and introduced Atlantic ranges via experimental field studies during which
lionfish and other, ecologically-similar reef fishes were caged and exposed to gnathiid infestation on shallow coral reefs.
Lionfish in both ranges had very few gnathiids when compared with other species, suggesting that lionfish are not highly
susceptible to infestation by generalist ectoparasitic gnathiids. While this pattern implies that release from gnathiid
infestation is unlikely to contribute to the success of lionfish as invaders, it does suggest that in environments with high
gnathiid densities, lionfish may have an advantage over species that are more susceptible to gnathiids. Also, because
lionfish are not completely resistant to gnathiids, our results suggest that lionfish could possibly have transported blood
parasites between their native Pacific and invaded Atlantic ranges
Analytical solutions for radiation-driven winds in massive stars - II: The δ-slow regime
Accurate mass-loss rates and terminal velocities from massive stars winds are essential to obtain synthetic spectra from radiative transfer calculations and to determine the evolutionary path of massive stars. From a theoretical point of view, analytical expressions for the wind parameters and velocity profile would have many advantages over numerical calculations that solve the complex non-linear set of hydrodynamic equations. In a previous work, we obtained an analytical description for the fast wind regime. Now, we propose an approximate expression for the line-force in terms of new parameters and obtain a velocity profile closed-form solution (in terms of the Lambert W function) for the δ-slow regime. Using this analytical velocity profile, we were able to obtain the mass-loss rates based on the m-CAK theory. Moreover, we established a relation between this new set of line-force parameters with the known stellar and m-CAK line-force parameters. To this purpose, we calculated a grid of numerical hydrodynamical models and performed a multivariate multiple regression. The numerical and our descriptions lead to good agreement between their values.Fil: Araya, I.. Universidad Mayor; ChileFil: Christen, A.. Universidad de Valparaíso; ChileFil: Cure, M.. Universidad de Valparaíso; ChileFil: Cidale, Lydia Sonia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Venero, Roberto Oscar José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Arcos, C.. Universidad de Valparaíso; ChileFil: Gormaz Matamala, A.. Universidad de Valparaíso; Chile. Universidad Adolfo Ibañez; ChileFil: Haucke, Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Escarate, P.. Universidad Austral de Chile; ChileFil: Clavería, H.. Pontificia Universidad Católica de Valparaíso; Chil
Differences in the gas and dust distribution in the transitional disk of a sun-like young star, PDS 70
We present ALMA 0.87 mm continuum, HCO+ J=4--3 emission line, and CO J=3--2
emission line data of the disk of material around the young, Sun-like star PDS
70. These data reveal the existence of a possible two component transitional
disk system with a radial dust gap of 0."2 +/- 0."05, an azimuthal gap in the
HCO+ J=4--3 moment zero map, as well as two bridge-like features in the gas
data. Interestingly these features in the gas disk have no analogue in the dust
disk making them of particular interest. We modeled the dust disk using the
Monte Carlo radiative transfer code HOCHUNK3D (Whitney et al. 2013) using a two
disk components. We find that there is a radial gap that extends from 15-60 au
in all grain sizes which differs from previous work
Imaging the disc rim and a moving close-in companion candidate in the pre-transitional disc of V1247 Orionis
This is the author accepted manuscript. The final version is available from EDP Sciences via the DOI in this record.Context. V1247 Orionis harbours a pre-transitional disc with a partially cleared gap. Earlier interferometric and polarimetric observations
revealed strong asymmetries both in the gap region and in the outer disc. The presence of a companion was inferred to explain
these asymmetric structures and the ongoing disc clearing.
Aims. Using an extensive set of multi-wavelength and multi-epoch observations we aimed to identify the origin of the previously
detected asymmetries.
Methods. We observed V1247 Ori at three epochs spanning ∼ 678 days using sparse aperture masking interferometry with
Keck/NIRC2 and VLT/NACO. In addition, we search for signs of accretion through VLT/SPHERE-ZIMPOL spectral differential
imaging in Hα and R-band continuum. Our SMA sub-millimetre interferometry in 880 µm continuum and in the CO(3-2) line allows
us to constrain the orientation and direction of rotation of the outer disc.
Results. We find the L’-band emission to be dominated by static features which trace forward-scattered dust emission from the
inner edge of the outer disc located to the north-east. In H- and K-band, we see evidence for a companion candidate that moved
systematically by 45◦ within the first ∼345 days. The separation of the companion candidate is not well constrained, but the observed
position angle change is consistent with Keplerian motion of a body located on a 6 au orbit. From the SMA CO moment map, the
location of the disc rim, and the detected orbital motion, we deduced the 3-dimensional orientation of the disc. We see no indication
of accretion in Hα and set upper limits for an accreting companion.
Conclusions. The measured contrast of the companion candidate in H and K is consistent with an actively accreting protoplanet.
Hence, we identify V1247 Ori as a unique laboratory for studying companion-disc interactions and disc clearing.We acknowledge support from an ERC
Starting Grant (Grant Agreement No. 639889), STFC Rutherford Fellowship
Article number, page 14 of 17
M. Willson et al.: Imaging the disc rim and companion candidate in V1247 Ori
(ST/J004030/1), STFC Rutherford Grant (ST/K003445/1), Marie SklodowskaCurie
CIG grant (Ref. 618910), and Philip Leverhulme Prize (PLP-2013-110).
We additionally acknowledge support from NASA KPDA grants (JPL-1452321,
1474717, 1485953, 1496788). The Submillimeter Array is a joint project between
the Smithsonian Astrophysical Observatory and the Academia Sinica Institute
of Astronomy and Astrophysics and is funded by the Smithsonian Institution
and the Academia Sinica. The authors wish to recognize and acknowledge
the very significant cultural role and reverence that the summit of Mauna Kea
has always had within the indigenous Hawaiian community. We are most fortunate
to have the opportunity to conduct observations from this mountain.Some
of the data presented herein were obtained at the W.M. Keck Observatory, which
is operated as a scientific partnership among the California Institute of Technology,
the University of California and the National Aeronautics and Space
Administration. The Observatory was made possible by the generous financial
support of the W.M. Keck Foundation. J. Kluska acknowledges support from the
research council of the KU Leuven under grant number C14/17/082. M. Curé
and S. Kanaan acknowledge financial support from Centro de Astrofísica de Valparaiso.
S. Kanaan thank the support of Fondecyt iniciacíon grant No. 11130702.
T. Muto is partially supported by JSPS KAKENHI grant No. 26800106
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