2,273 research outputs found
3 mm GMVA Observations of Total and Polarized Emission from Blazar and Radio Galaxy Core Regions
We present total and linearly polarized 3 mm Global mm-VLBI Array images of a
sample of blazars and radio galaxies from the VLBA-BU-BLAZAR 7 mm monitoring
program designed to probe the innermost regions of active galactic nuclei (AGN)
jets and locate the sites of gamma-ray emission observed by the Fermi-LAT. The
lower opacity at 3 mm and improved angular resolution, on the order of 50
microarcseconds, allow us to distinguish features in the jet not visible in the
7 mm VLBA data. We also compare two different methods used for the calibration
of instrumental polarisation and we analyze the resulting images for some of
the sources in the sample.Comment: Polarised Emission from Astrophysical Jets, June 12-16, 2017,
Ierapetra, Greec
Spatially resolved origin of mm-wave linear polarization in the nuclear region of 3C 84
We report results from a deep polarization imaging of the nearby radio galaxy 3C 84 (NGC 1275). The source was observed with the Global Millimeter VLBI Array (GMVA) at 86 GHz at an ultra-high angular resolution of 50μas (corresponding to 250R). We also add complementary multi-wavelength data from the Very Long Baseline Array (VLBA; 15 & 43 GHz) and from the Atacama Large Millimeter/submillimeter Array (ALMA; 97.5, 233.0, and 343.5 GHz). At 86 GHz, we measure a fractional linear polarization of ~ 2% in the VLBI core region. The polarization morphology suggests that the emission is associated with an underlying limb-brightened jet. The fractional linear polarization is lower at 43 and 15 GHz (~ 0.3-0.7% and < 0.1%, respectively). This suggests an increasing linear polarization degree towards shorter wavelengths on VLBI scales. We also obtain a large rotation measure (RM) of ~ 10⁵⁻⁶ rad/m² in the core at ≳43 GHz. Moreover, the VLBA 43 GHz observations show a variable RM in the VLBI core region during a small flare in 2015. Faraday depolarization and Faraday conversion in an inhomogeneous and mildly relativistic plasma could explain the observed linear polarization characteristics and the previously measured frequency dependence of the circular polarization. Our Faraday depolarization modeling suggests that the RM most likely originates from an external screen with a highly uniform RM distribution. To explain the large RM value, the uniform RM distribution, and the RM variability, we suggest that the Faraday rotation is caused by a boundary layer in a transversely stratified jet. Based on the RM and the synchrotron spectrum of the core, we provide an estimate for the magnetic field strength and the electron density of the jet plasma.Accepted manuscrip
Phenomenology of the Equivalence Principle with Light Scalars
Light scalar particles with couplings of sub-gravitational strength, which
can generically be called 'dilatons', can produce violations of the equivalence
principle. However, in order to understand experimental sensitivities one must
know the coupling of these scalars to atomic systems. We report here on a study
of the required couplings. We give a general Lagrangian with five independent
dilaton parameters and calculate the "dilaton charge" of atomic systems for
each of these. Two combinations are particularly important. One is due to the
variations in the nuclear binding energy, with a sensitivity scaling with the
atomic number as . The other is due to electromagnetism. We compare
limits on the dilaton parameters from existing experiments.Comment: 5 page
Modelling the strongest silicate emission features of local type 1 AGN
We measure the 10 and m silicate features in a sample of 67 local
() type 1 active galactic nuclei (AGN) with available {\it Spitzer}
spectra dominated by non-stellar processes. We find that the m silicate
feature peaks at m with a strength (Si = ln
f(spectrum)/f(continuum)) of , while the
m one peaks at m with a strength of
. We select from this sample sources with the strongest
10m silicate strength (, 10 objects). We carry
out a detailed modeling of the IRS/{\it Spitzer} spectra by comparing several
models that assume different geometries and dust composition: a smooth torus
model, two clumpy torus models, a two-phase medium torus model, and a
disk+outflow clumpy model. We find that the silicate features are well modeled
by the clumpy model of Nenkova et al. 2008, and among all models those
including outflows and complex dust composition are the best (Hoenig et al.
2017). We note that even in AGN-dominated galaxies it is usually necessary to
add stellar contributions to reproduce the emission at the shortest
wavelengths.Comment: Accepted for publication in Ap
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Hut-like pillar array Si Solar Cells
A good texturing pattern for solar cells needs to combine low Reflectance over a large wavelength range and low surface recombination to maximize the output. Nanowire and pyramid patterns offer low Reflectance in the longer and shorter wavelength regions respectively. This paper introduces an exciting new “hut” like texturing pattern with excellent performance, improving that of nanowires and pyramids; over the long and short wavelength ranges respectively. Furthermore, we analyze the effect of different structural parameters such as height, diameter, Surface Coverage (SC) and ϑ, on the solar cell performance
The Evolving Demographic and Health Transition in Four Low- and Middle-Income Countries: Evidence from Four Sites in the INDEPTH Network of Longitudinal Health and Demographic Surveillance Systems.
This paper contributes evidence documenting the continued decline in all-cause mortality and changes in the cause of death distribution over time in four developing country populations in Africa and Asia. We present levels and trends in age-specific mortality (all-cause and cause-specific) from four demographic surveillance sites: Agincourt (South Africa), Navrongo (Ghana) in Africa; Filabavi (Vietnam), Matlab (Bangladesh) in Asia. We model mortality using discrete time event history analysis. This study illustrates how data from INDEPTH Network centers can provide a comparative, longitudinal examination of mortality patterns and the epidemiological transition. Health care systems need to be reconfigured to deal simultaneously with continuing challenges of communicable disease and increasing incidence of non-communicable diseases that require long-term care. In populations with endemic HIV, long-term care of HIV patients on ART will add to the chronic care needs of the community
Pirfenidone in idiopathic pulmonary fibrosis:expert panel discussion on the management of drug-related adverse events
Pirfenidone is currently the only approved therapy for idiopathic pulmonary fibrosis, following studies demonstrating that treatment reduces the decline in lung function and improves progression-free survival. Although generally well tolerated, a minority of patients discontinue therapy due to gastrointestinal and skin-related adverse events (AEs). This review summarizes recommendations based on existing guidelines, research evidence, and consensus opinions of expert authors, with the aim of providing practicing physicians with the specific clinical information needed to educate the patient and better manage pirfenidone-related AEs with continued pirfenidone treatment. The main recommendations to help prevent and/or mitigate gastrointestinal and skin-related AEs include taking pirfenidone during (or after) a meal, avoiding sun exposure, wearing protective clothing, and applying a broad-spectrum sunscreen with high ultraviolet (UV) A and UVB protection. These measures can help optimize AE management, which is key to maintaining patients on an optimal treatment dose.Correction in: Advances in Therapy, Volume 31, Issue 5, pp 575-576 , doi: 10.1007/s12325-014-0118-8</p
Phytoestrogens
Collectively, plants contain several different families of natural products among which are compounds with weak estrogenic or antiestrogenic activity toward mammals. These compounds, termed phytoestrogens, include certain isoflavonoids, flavonoids, stilbenes, and lignans. The best-studied dietary phytoestrogens are the soy isoflavones and the flaxseed lignans. Their perceived health beneficial properties extend beyond hormone-dependent breast and prostate cancers and osteoporosis to include cognitive function, cardiovascular disease, immunity and inflammation, and reproduction and fertility. In the future, metabolic engineering of plants could generate novel and exquisitely controlled dietary sources with which to better assess the potential health beneficial effects of phytoestrogens
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