69 research outputs found
SO ORDERED: A Textual Analysis of United Statesâ Governorsâ Press Release Responses to the COVID-19 Pandemic
The COVID-19 pandemic presents a unique environment from which each individual state, in the United States, has been forced to address their publics. In order to understand how each state has engaged with this pandemic, a textual analysis of each stateâs governorâs first press release was conducted; five thematic trends were identified. Through use of the social trust approach to risk communication and the contingency theory of strategic conflict management (using external threat variables), the implications of these press releases are discussed
Complex Faraday depth structure of Active Galactic Nuclei as revealed by broadband radio polarimetry
We present a detailed study of the Faraday depth structure of four bright (>
1 Jy), strongly polarized, unresolved, radio-loud quasars. The Australia
Telescope Compact Array (ATCA) was used to observe these sources with 2 GHz of
instantaneous bandwidth from 1.1 to 3.1 GHz. This allowed us to spectrally
resolve the polarization structure of spatially unresolved radio sources, and
by fitting various Faraday rotation models to the data, we conclusively
demonstrate that two of the sources cannot be described by a simple rotation
measure (RM) component modified by depolarization from a foreground Faraday
screen. Our results have important implications for using background
extragalactic radio sources as probes of the Galactic and intergalactic
magneto-ionic media as we show how RM estimations from narrow-bandwidth
observations can give erroneous results in the presence of multiple interfering
Faraday components. We postulate that the additional RM components arise from
polarized structure in the compact inner regions of the radio source itself and
not from polarized emission from Galactic or intergalactic foreground regions.
We further suggest that this may contribute significantly to any RM
time-variability seen in RM studies on these angular scales. Follow-up,
high-sensitivity VLBI observations of these sources will directly test our
predictions.Comment: Accepted for publication in MNRAS. 19 pages, 15 figures, 4 table
Bright AGN Source List from the First Three Months of the Fermi Large Area Telescope All-Sky Survey
The first three months of sky-survey operation with the Fermi Gamma Ray Space
Telescope (Fermi) Large Area Telescope (LAT) reveals 132 bright sources at
|b|>10 deg with test statistic greater than 100 (corresponding to about 10
sigma). Two methods, based on the CGRaBS, CRATES and BZCat catalogs, indicate
high-confidence associations of 106 of these sources with known AGNs. This
sample is referred to as the LAT Bright AGN Sample (LBAS). It contains two
radio galaxies, namely Centaurus A and NGC 1275, and 104 blazars consisting of
57 flat spectrum radio quasars (FSRQs), 42 BL Lac objects, and 5 blazars with
uncertain classification. Four new blazars were discovered on the basis of the
LAT detections. Remarkably, the LBAS includes 10 high-energy peaked BL Lacs
(HBLs), sources which were so far hard to detect in the GeV range. Another 10
lower-confidence associations are found. Only thirty three of the sources, plus
two at |b|>10 deg, were previously detected with EGRET, probably due to the
variable nature of these sources. The analysis of the gamma-ray properties of
the LBAS sources reveals that the average GeV spectra of BL Lac objects are
significantly harder than the spectra of FSRQs. No significant correlation
between radio and peak gamma-ray fluxes is observed. Blazar log N - log S and
luminosity functions are constructed to investigate the evolution of the
different blazar classes, with positive evolution indicated for FSRQs but none
for BLLacs. The contribution of LAT-blazars to the total extragalactic
gamma-ray intensity is estimated.Comment: Submitted to ApJ. Not yet refereed. 61 pages, 26 figure
PEGylation improves the receptor-mediated transfection efficiency of peptide-targeted, self-assembling, anionic nanocomplexes
Non-viral vector formulations comprise typically complexes of nucleic acids with cationic polymers or lipids. However, for in vivo applications cationic formulations suffer from problems of poor tissue penetration, non-specific binding to cells, interaction with serum proteins and cell adhesion molecules and can lead to inflammatory responses. Anionic formulations may provide a solution to these problems but they have not been developed to the same extent as cationic formulations due to difficulties of nucleic acid packaging and poor transfection efficiency. We have developed novel PEGylated, anionic nanocomplexes containing cationic targeting peptides that act as a bridge between PEGylated anionic liposomes and plasmid DNA. At optimized ratios, the components self-assemble into anionic nanocomplexes with a high packaging efficiency of plasmid DNA. Anionic PEGylated nanocomplexes were resistant to aggregation in serum and transfected cells with a far higher degree of receptor-targeted specificity than their homologous non-PEGylated anionic and cationic counterparts. Gadolinium-labeled, anionic nanoparticles, administered directly to the brain by convection-enhanced delivery displayed improved tissue penetration and dispersal as well as more widespread cellular transfection than cationic formulations. Anionic PEGylated nanocomplexes have widespread potential for in vivo gene therapy due to their targeted transfection efficiency and ability to penetrate tissues
Observations of a nearby filament of galaxy clusters with the Sardinia Radio Telescope
We report the detection of diffuse radio emission which might be connected to
a large-scale filament of the cosmic web covering a 8deg x 8deg area in the
sky, likely associated with a z~0.1 over-density traced by nine massive galaxy
clusters. In this work, we present radio observations of this region taken with
the Sardinia Radio Telescope. Two of the clusters in the field host a powerful
radio halo sustained by violent ongoing mergers and provide direct proof of
intra-cluster magnetic fields. In order to investigate the presence of
large-scale diffuse radio synchrotron emission in and beyond the galaxy
clusters in this complex system, we combined the data taken at 1.4 GHz obtained
with the Sardinia Radio Telescope with higher resolution data taken with the
NRAO VLA Sky Survey. We found 28 candidate new sources with a size larger and
X-ray emission fainter than known diffuse large-scale synchrotron cluster
sources for a given radio power. This new population is potentially the tip of
the iceberg of a class of diffuse large-scale synchrotron sources associated
with the filaments of the cosmic web. In addition, we found in the field a
candidate new giant radio galaxy.Comment: 35 pages, 30 figures, MNRAS Accepted, A high-resolution version of
the paper can be found at the link
http://erg.oa-cagliari.inaf.it/preprints/paper_filament.pd
The Eleventh and Twelfth Data Releases of the Sloan Digital Sky Survey: Final Data from SDSS-III
The third generation of the Sloan Digital Sky Survey (SDSS-III) took data from 2008 to 2014 using the original SDSS wide-field imager, the original and an upgraded multi-object fiber-fed optical spectrograph, a new near-infrared high-resolution spectrograph, and a novel optical interferometer. All of the data from SDSS-III are now made public. In particular, this paper describes Data Release 11 (DR11) including all data acquired through 2013 July, and Data Release 12 (DR12) adding data acquired through 2014 July (including all data included in previous data releases), marking the end of SDSS-III observing. Relative to our previous public release (DR10), DR12 adds one million new spectra of galaxies and quasars from the Baryon Oscillation Spectroscopic Survey (BOSS) over an additional 3000 deg2 of sky, more than triples the number of H-band spectra of stars as part of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE), and includes repeated accurate radial velocity measurements of 5500 stars from the Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS). The APOGEE outputs now include the measured abundances of 15 different elements for each star. In total, SDSS-III added 5200 deg2 of ugriz imaging; 155,520 spectra of 138,099 stars as part of the Sloan Exploration of Galactic Understanding and Evolution 2 (SEGUE-2) survey; 2,497,484 BOSS spectra of 1,372,737 galaxies, 294,512 quasars, and 247,216 stars over 9376 deg2; 618,080 APOGEE spectra of 156,593 stars; and 197,040 MARVELS spectra of 5513 stars. Since its first light in 1998, SDSS has imaged over 1/3 of the Celestial sphere in five bands and obtained over five million astronomical spectra. \ua9 2015. The American Astronomical Society
Past, Present, and Future X-Ray and Gamma-Ray Missions
X- and -ray astronomy began in the early sixties of the last century with balloons flights, sounding rocket experiment and satellites. Long before space satellite detected X- and -rays emitted by cosmic sources, scientists had known that the Universe should be producing these photons. In this chapter we provided an overview of past and present missions that has made the X- and -ray astronomy an integral part of astronomical research, and prospects of future developments
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