8,130 research outputs found
Intrinsic Brightness Temperatures of AGN Jets
We present a new method for studying the intrinsic brightness temperatures of
the parsec-scale jet cores of Active Galactic Nuclei (AGN). Our method uses
observed superluminal motions and observed brightness temperatures for a large
sample of AGN to constrain the characteristic intrinsic brightness temperature
of the sample as a whole. To study changes in intrinsic brightness temperature,
we assume that the Doppler factors of individual jets are constant in time as
justified by their relatively small changes in observed flux density. We find
that in their median-low brightness temperature state, the sources in our
sample have a narrow range of intrinsic brightness temperatures centered on a
characteristic temperature, T_int = 3 x 10^10 K, which is close to the value
expected for equipartition, when the energy in the radiating particles equals
the energy stored in the magnetic fields. However, in their maximum brightness
state, we find that sources in our sample have a characteristic intrinsic
brightness temperature greater than 2 x 10^11 K, which is well in excess of the
equipartition temperature. In this state, we estimate the energy in radiating
particles exceeds the energy in the magnetic field by a factor of ~ 10^5. We
suggest that the excess of particle energy when sources are in their maximum
brightness state is due to injection or acceleration of particles at the base
of the jet. Our results suggest that the common method of estimating jet
Doppler factors by using a single measurement of observed brightness
temperature and/or the assumption of equipartition may lead to large scatter or
systematic errors in the derived values.Comment: 4 pages, 2 figures, Accepted to Appear in ApJ Letter
Use of Nebulized Amphotericin B in the Treatment of Allergic Bronchopulmonary Aspergillosis in Cystic Fibrosis
Background. Systemic steroids and adjunctive antifungal therapy are the cornerstone in treating allergic bronchopulmonary aspergillosis (ABPA) in the context of CF. Aim. Evaluate the use of inhaled amphotericin B (iAMB) as antifungal agent in this context. Methods. Report of 7 CF patients with recurrent or difficult to treat ABPA and failure to taper systemic corticosteroids treated with AMB deoxycholate (AMB-d) (Fungizone 25 mg 3× a week) or AMB lipid complex (ABLC) (Abelcet 50 mg twice weekly). Successful therapy was defined as steroid withdrawal without ABPA relapse within 12 months. Results. Therapy was successful in 6 of 7 patients treated with iAMB. In 5/6, lung function improved. The patient with treatment failure has concomitant MAC lung infection. Conclusion. Inhaled AMB may be an alternative to commonly used adjunctive antifungal therapy in the treatment of ABPA. More data are needed on safety and efficacy
Kinematics of parsec-scale structures in AGN: the 2cm VLBA Survey
We are investigating the kinematics of jets in active galactic nuclei on
parsec scales by studying a representative population of sources. This study is
being carried out using the Very Long Baseline Array at 15 GHz, with more than
800 images taken since 1994. In this contribution we present an overview of the
diversity of kinematics for a complete sample of sources.Comment: Proceedings of the 6th European VLBI Network Symposium, Ros E.,
Porcas R.W., Lobanov, A.P., & Zensus, J.A. (eds), MPIfR, Bonn, Germany. 2
pages, 3 figures, needs evn2002.cls style fil
Variability and Velocity of Superluminal Sources
We investigate the relation between the Doppler factor determined from
variations in total flux at 22 and 37 GHz, and the apparent transverse velocity
determined from VLBA observations at 2 cm. The data are consistent with the
relativistic beaming theory for compact radio sources, in that the distribution
of beta_{app}/delta_{var}, for 30 quasars, is roughly consistent with a Monte
Carlo simulation. The intrinsic temperature appears to be ~2x10^{10} K, close
to the "equipartition value" calculated by Readhead (1994). We deduce the
distribution of Lorentz factors for a group of 48 sources; the values range up
to about gamma=40.Comment: To be published in "Radio Astronomy at the Fringe", ASP Conf. Ser.
Vol. 300, J. A. Zensus, M. H. Cohen, & E. Ros (eds.), 8 pages, 3 figures,
needs rafringe.st
Molecular footprint of drug-selective pressure in a human immunodeficiency virus transmission chain
Known human immunodeficiency virus (HIV) transmission histories are invaluable models for investigating the evolutionary and transmission dynamics of the virus and to assess the accuracy of phylogenetic reconstructions. Here we have characterized an HIV-1 transmission chain consisting of nine infected patients, almost all of whom were treated with antiviral drugs at later stages of infection. Partial pol and env gp41 regions of the HIV genome were directly sequenced from plasma viral RNA for at least one sample from each patient. Phylogenetic analyses in pol using likelihood methods inferred an evolutionary history not fully compatible with the known transmission history. This could be attributed to parallel evolution of drug resistance mutations resulting in the incorrect clustering of multidrug-resistant virus. On the other hand, a fully compatible phylogenetic tree was reconstructed from the env sequences. We were able to identify and quantify the molecular footprint of drug-selective pressure in pol using maximum likelihood inference under different codon substitution models. An increased fixation rate of mutations in the HIV population of the multidrug-resistant patient was demonstrated using molecular clock modeling. We show that molecular evolutionary analyses, guided by a known transmission history, can reveal the presence of confounding factors like natural selection and caution should be taken when accurate descriptions of HIV evolution are required.status: publishe
The Effect of cold-chain re-introduction on the molecular integrity of rocuronium bromide
https://drive.google.com/file/d/1Fnc74HliOt37xUpPyKEWwSMqHW5-sNi-/view?usp=sharinghttps://drive.google.com/drive/folders/1cmCcrZEfrPhL1J0pt4py-9qhYXnOlHn9?usp=sharinghttps://drive.google.com/drive/folders/1_RCPybSRd1j9iE0G4y8G7Al7ECn74bLy?usp=sharin
Lack of knowledge and experience highlights the need for a clear paediatric organ and tissue donation protocol in the Netherlands
Aim This study explored the attitudes of medical professionals to organ and tissue donation in paediatric intensive care units (PICUs) and neonatal intensive care units (NICUs) in the Netherlands. It also examined their compliance with the existing Dutch donation protocol and assessed whether a paediatric donation protocol was needed. Methods We invited 966 professionals working in all eight PICUs and the two largest NICUs to complete an online survey from December 2016 until April 2017. Results A quarter (25%) took part and they included PICU intensivists, neonatologists, nurses and other health and allied professionals. Most were female and nurses. More than half (54%) of the PICU respondents considered paediatric organ donation to be very important and 53% supported tissue donation. In contrast, only 22% of the NICU respondents believed that both neonatal organ and tissue donation were very important. Familiarity and compliance with the existing national donation protocol were low. PICU nurses had significantly less experience than PICU intensivists and felt less comfortable with the donation process. None of the NICU respondents had prior donation experience. Conclusion Paediatric intensive care units and NICU professionals lack specialised knowledge and experience on organ and tissue donation. A comprehensive and clear paediatric donation protocol is clearly needed
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