23,921 research outputs found
New Measurements of the Radio Photosphere of Mira based on Data from the JVLA and ALMA
We present new measurements of the millimeter wavelength continuum emission
from the long period variable Mira ( Ceti) at frequencies of 46 GHz, 96 GHz,
and 229 GHz (~7 mm, 3 mm, and 1 mm) based on observations obtained
with the Jansky Very Large Array (JVLA) and the Atacama Large
Millimeter/submillimeter Array (ALMA). The measured millimeter flux densities
are consistent with a radio photosphere model derived from previous
observations, where flux density, . The stellar disk
is resolved, and the measurements indicate a decrease in the size of the radio
photosphere at higher frequencies, as expected if the opacity decreases at
shorter wavelengths. The shape of the radio photosphere is found to be slightly
elongated, with a flattening of ~10-20%. The data also reveal evidence for
brightness non-uniformities on the surface of Mira at radio wavelengths. Mira's
hot companion, Mira B was detected at all three observed wavelengths, and we
measure a radius for its radio-emitting surface of
cm. The data presented here highlight the power of the JVLA and ALMA for the
study of the atmospheres of evolved stars.Comment: Accepted to ApJ; 27 pages, 7 figure
5-micron photometry of late-type dwarfs
We present narrowband-M photometry of nine low-mass dwarfs with spectral
types ranging from M2.5 to L0.5. Combining the (L'-M') colours derived from our
observations with data from the literature, we find colours consistent with a
Rayleigh-Jeans flux distribution for spectral types earlier than M5, but
enhanced F_3.8/F_4.7 flux ratios (negative (L'-M') colours) at later spectral
types. This probably reflects increased absorption at M' due to the CO
fundamental band. We compare our results against recent model predictions and
briefly discuss the implications.Comment: accepted for the Astronomical Journa
Trigonometric Parallaxes of Massive Star Forming Regions: VIII. G12.89+0.49, G15.03-0.68 (M17) and G27.36-0.16
We report trigonometric parallaxes for three massive star forming regions,
corresponding to distances of kpc for G12.89+0.49 (also
known as IRAS 18089-1732), kpc for G15.03-0.68 (in the
M17 region), and kpc for G27.36-0.16. Both G12.89+0.49 and
G15.03-0.68 are located in the Carina-Sagittarius spiral arm
Radio signatures of solar energetic particles during the 23rd solar cycle
We present the association rates between solar energetic particles (SEPs) and
the radio emission signatures in the corona and IP space during the entire
solar cycle 23. We selected SEPs associated with X and M-class flares from the
visible solar hemisphere. All SEP events are also accompanied by coronal mass
ejections. Here, we focus on the correlation between the SEP events and the
appearance of radio type II, III and IV bursts on dynamic spectra. For this we
used the available radio data from ground-based stations and the Wind/WAVES
spacecraft. The associations are presented separately for SEP events
accompanying activity in the eastern and western solar hemisphere. We find the
highest association rate of SEP events to be with type III bursts, followed by
types II and IV. Whereas for types III and IV no longitudinal dependence is
noticed, these is a tendency for a higher SEP-association rate with type II
bursts in the eastern hemisphere. A comparison with reports from previous
studies is briefly discussed.Comment: http://adsabs.harvard.edu.ezproxy.obspm.fr/abs/2013CEAB...37..541
Adherence to prophylaxis in adolescents and young adults with severe haemophilia, A qualitative study with patients
© 2018 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.Abstract Introduction: Reported levels of adherence to prophylaxis among young people with haemophilia (YPH) vary widely and are predominately based on estimations made by healthcare professionals and parents. Reasons for (non)adherence among YPH in particular have not been evidenced. Aim: to examine experiences in relation to prophylaxis with YPH themselves, and barriers and facilitators to their adherence. Methods: 11 Participants were recruited in five haemophilia centres across England and Wales. All patients who met the inclusion criteria (aged 12-25, diagnosed with haemophilia, on prophylaxis) were approached during a routine check-up appointment, and all participants who agreed to take part were interviewed. Interviews were audio recorded, transcribed and analysed using Interpretative Phenomenological Analysis. Results: Self-reported adherence to prophylaxis was good. Few participants admitted to intentionally skipping injections although they reported sometimes forgetting. However, due to the increasingly personalised and flexible approach to prophylaxis, adherence is not straightforward to define. Barriers to adherence included a busy lifestyle, dislike of the intravenous injection, venous access issues, anxiety or stress and being out of one’s normal routine. Support was an important facilitator to adherence, including support from health professionals at the haemophilia centre as well as friends. Parents appear to be very involved with their sons’ haemophilia management, even after their sons leave home. Conclusion: What this study adds is that the increasingly flexible and personalized approach to managing prophylaxis in haemophilia may sometimes lead to confusion around treatment frequency and dosing. This may lead to accidental non-adherence, which is distinct from both skipping and forgetting. Advice from haemophilia teams may not always be consistent, and is likely to be interpreted differently by different individuals. Some additional training and education of patients and their families to increase their knowledge and skills around prophylaxis may reduce this confusion and therefore is likely to improve adherence further.Peer reviewedFinal Published versio
Decoherence of Einstein-Podolsky-Rosen steering
We consider two systems A and B that share Einstein-Podolsky-Rosen (EPR)
steering correlations and study how these correlations will decay, when each of
the systems are independently coupled to a reservoir. EPR steering is a
directional form of entanglement, and the measure of steering can change
depending on whether the system A is steered by B, or vice versa. First, we
examine the decay of the steering correlations of the two-mode squeezed state.
We find that if the system B is coupled to a reservoir, then the decoherence of
the steering of A by B is particularly marked, to the extent that there is a
sudden death of steering after a finite time. We find a different directional
effect, if the reservoirs are thermally excited. Second, we study the
decoherence of the steering of a Schr\"odinger cat state, modeled as the
entangled state of a spin and harmonic oscillator, when the macroscopic system
(the cat) is coupled to a reservoir
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