743 research outputs found
X-ray study of a sample of FR0 radio galaxies: unveiling the nature of the central engine
FR0s are compact radio sources that represent the bulk of the Radio-Loud (RL)
AGN population, but they are still poorly understood. Pilot studies on these
sources have been already performed at radio and optical wavelengths: here we
present the first X-ray study of a sample of 19 FR0 radio galaxies selected
from the SDSS/NVSS/FIRST sample of Best & Heckman (2012), with redshift
0.15, radio size 10 kpc and optically classified as low-excitation
galaxies (LEG). The X-ray spectra are modeled with a power-law component
absorbed by Galactic column density with, in some cases, a contribution from
thermal extended gas. The X-ray photons are likely produced by the jet as
attested by the observed correlation between X-ray (2-10 keV) and radio (5 GHz)
luminosities, similar to FRIs. The estimated Eddington-scaled luminosities
indicate a low accretion rate. Overall, we find that the X-ray properties of
FR0s are indistinguishable from those of FRIs, thus adding another similarity
between AGN associated with compact and extended radio sources. A comparison
between FR0s and low luminosity BL Lacs, rules out important beaming effects in
the X-ray emission of the compact radio galaxies. FR0s have different X-ray
properties with respect to young radio sources (e.g. GPS/CSS sources),
generally characterized by higher X-ray luminosities and more complex spectra.
In conclusion, the paucity of extended radio emission in FR0s is probably
related to the intrinsic properties of their jets that prevent the formation of
extended structures, and/or to intermittent activity of their engines.Comment: Accepted for publication in MNRAS (18 pages, 4 figures
Illness in Returned Travelers and Immigrants/Refugees: The 6-Year Experience of Two Australian Infectious Diseases Units.
BACKGROUND: Data comparing returned travelers and immigrants/refugees managed in a hospital setting is lacking. METHODS: We prospectively collected data on 1,106 patients with an illness likely acquired overseas who presented to two hospital-based Australian infectious diseases units over a 6-year period. RESULTS: Eighty-three percent of patients were travelers and 17% immigrants/refugees. In travelers, malaria (19%), gastroenteritis/diarrhea (15%), and upper respiratory tract infection (URTI) (7%) were the most common diagnoses. When compared with immigrants/refugees, travelers were significantly more likely to be diagnosed with gastroenteritis/diarrhea [odds ratio (OR) 8], malaria (OR 7), pneumonia (OR 6), URTI (OR 3), skin infection, dengue fever, typhoid/paratyphoid fever, influenza, and rickettsial disease. They were significantly less likely to be diagnosed with leprosy (OR 0.03), chronic hepatitis (OR 0.04), tuberculosis (OR 0.05), schistosomiasis (OR 0.3), and helminthic infection (OR 0.3). In addition, travelers were more likely to present within 1 month of entry into Australia (OR 96), and have fever (OR 8), skin (OR 6), gastrointestinal (OR 5), or neurological symptoms (OR 5) but were less likely to be asymptomatic (OR 0.1) or have anaemia (OR 0.4) or eosinophilia (OR 0.3). Diseases in travelers were more likely to have been acquired via a vector (OR 13) or food and water (OR 4), and less likely to have been acquired via the respiratory (OR 0.2) or skin (OR 0.6) routes. We also found that travel destination and classification of traveler can significantly influence the likelihood of a specific diagnosis in travelers. Six percent of travelers developed a potentially vaccine-preventable disease, with failure to vaccinate occurring in 31% of these cases in the pretravel medical consultation. CONCLUSIONS: There are important differences in the spectrum of illness, clinical features, and mode of disease transmission between returned travelers and immigrants/refugees presenting to hospital-based Australian infectious diseases units with an illness acquired overseas
Clustering in 18O - absolute determination of branching ratios via high-resolution particle spectroscopy
The determination of absolute branching ratios for high-energy states in light nuclei is an important and useful tool for probing the underlying nuclear structure of individual resonances: for example, in establishing the tendency of an excited state towards
α
-cluster structure. Difficulty arises in measuring these branching ratios due to similarities in available decay channels, such as (
18
O,
n
) and (
18
O,
2
n
), as well as differences in geometric efficiencies due to population of bound excited levels in daughter nuclei. Methods are presented using Monte Carlo techniques to overcome these issues
Radio morphology-accretion mode link in FRII low-excitation radio galaxies
Fanaroff-Riley II low-excitation radio galaxies (FRII-LERGs) are
characterized by weak nuclear excitation on pc-scales and by properties typical
of powerful FRIIs (defined as high-excitation, hereafter HERGs/BLRGs) on
kp-scales. Since a link between the accretion properties and the power of the
produced jets is expected both from theory and observations, their nature is
still debated. In this work we investigate the X-ray properties of a complete
sample of 19 FRII-LERGs belonging to the 3CR catalog, exploiting Chandra and
XMM-Newton archival data. We also analyze 32 FRII-HERGs/BLRGs with Chandra data
as a control sample. We compared FRII-LERG and FRII-HERG/BLRG X-ray properties
and optical data available in literature to obtain a wide outlook of their
behavior. The low accretion rate estimates for FRII-LERGs, from both X-ray and
optical bands, allow us to firmly reject the hypothesis for that they are the
highly obscured counterpart of powerful FRII-HERGs/BLRGs. Therefore, at least
two hypothesis can be invoked to explain the FRII-LERGs nature: (i) they are
evolving from classical FRIIs because of the depletion of accreting cold gas in
the nuclear region, while the extended radio emission is the heritage of a past
efficiently accreting activity; (ii) they are an intrinsically distinct class
of objects with respect to classical FRIs/FRIIs. Surprisingly, in this
direction a correlation between accretion rates and environmental richness is
found in our sample. The richer the environment, the more inefficient is the
accretion. In this framework, the FRII-LERGs are intermediate between FRIs and
FRII-HERGs/BLRGs both in terms of accretion rate and environment.Comment: 13 pages, 7 figures, Accepted for publication in MNRA
PHARAO Laser Source Flight Model: Design and Performances
In this paper, we describe the design and the main performances of the PHARAO
laser source flight model. PHARAO is a laser cooled cesium clock specially
designed for operation in space and the laser source is one of the main
sub-systems. The flight model presented in this work is the first
remote-controlled laser system designed for spaceborne cold atom manipulation.
The main challenges arise from mechanical compatibility with space constraints,
which impose a high level of compactness, a low electric power consumption, a
wide range of operating temperature and a vacuum environment. We describe the
main functions of the laser source and give an overview of the main
technologies developed for this instrument. We present some results of the
qualification process. The characteristics of the laser source flight model,
and their impact on the clock performances, have been verified in operational
conditions.Comment: Accepted for publication in Review of Scientific Instrument
The MURALES survey. I. A dual AGN in the radio galaxy 3C459?
We observed the FRII radio galaxy 3C459 (z=0.22) with the MUSE spectrograph
at the Very Large Telescope (VLT) as part of the MURALES project (a MUse RAdio
Loud Emission line Snapshot survey). We detected diffuse nuclear emission and a
filamentary ionized gas structure forming a one-sided, triangular-shaped region
extending out to 80 kpc. The central emission line region is dominated by
two compact knots of similar flux: the first (N1) cospatial with the radio core
and the (N2) second located 1.2" (5.3 kpc) to the SE. The two regions differ
dramatically from the point of view of velocity (with an offset of ~400 km/s),
line widths, and line ratios. This suggests that we are observing a dual AGN
system formed by a radio loud AGN and type 2 QSO companion, which is the result
of the recent merger that also produced its disturbed host morphology. The
alternative possibility that N2 is just a bright emission line knot resulting
from, for example, a jet-cloud interaction, is disfavored because of 1) the
presence of a high ionization bicone whose apex is located at N2; 2) the
observed narrow line widths; 3) its line luminosity (~10^42 erg s-1) typical of
luminous QSOs; and 4) its location, which is offset from the jet path. The
putative secondary AGN must be highly obscured, since we do not detect any
emission in the Chandra and infrared Hubble Space Telescope images.Comment: 6 pages, 6 figures, A&A in pres
Effects of coupling to breakup in the 6,7 Li + 64 Zn systems at near-barrier energies
Elastic scattering angular distributions for the weakly bound nucleus Li7 on Zn64 have been measured in a wide angular range at energies around the Coulomb barrier. The present experimental data and our previously measured elastic scattering data for the system Li6+Zn64 have been analyzed within the continuum-discretized coupled-channels method, where the resonant and nonresonant states of the projectile are taken into account. In this theoretical framework, we have also analyzed our previously measured excitation functions of elastic scattering at backward angles and the corresponding barrier distributions for the same systems. A good agreement between the experimental data and the calculations has been observed. The obtained results, besides confirming the importance of the coupling to the breakup channels in collisions with weakly bound nuclei, show that, in the case of Li6, the inclusion of the resonant states of the projectile produces non-negligible effects.Ministerio de Economía y Competitividad (España) FIS2013-41994-PJunta de Andalucía FQM160 P07-FQM-02894Programa Consolider-Ingenio 2010 (España) CSD2007-0004
Lot-to-lot consistency of a tetravalent dengue vaccine in healthy adults in Australia: a randomised study
Background: The recombinant yellow fever-17D-dengue virus, live, attenuated, tetravalent dengue vac-cine (CYD-TDV) has undergone extensive clinical trials. Here safety and consistency of immunogenicityof phase III manufacturing lots of CYD-TDV were evaluated and compared with a phase II lot and placeboin a dengue-naïve population.Methods: Healthy 18–60 year-olds were randomly assigned in a 3:3:3:3:1 ratio to receive three sub-cutaneous doses of either CYD-TDV from any one of three phase III lots or a phase II lot, or placebo,respectively in a 0, 6, 12 month dosing schedule. Neutralising antibody geometric mean titres (PRNT50GMTs) for each of the four dengue serotypes were compared in sera collected 28 days after the thirdvaccination—equivalence among lots was demonstrated if the lower and upper limits of the two-sided95% CIs of the GMT ratio were ≥0.5 and ≤2.0, respectively.Results: 712 participants received vaccine or placebo and 614 (86%) completed the study; 17 (2.4%) par-ticipants withdrew after adverse events. Equivalence of phase III lots was demonstrated for 11 of 12pairwise comparisons. One of three comparisons for serotype 2 was not statistically equivalent. GMTsfor serotype 2 in phase III lots were close to each other (65.9, 44.1 and 58.1, respectively).Conclusions: Phase III lots can be produced in a consistent manner with predictable immune responseand acceptable safety profile similar to previously characterised phase II lots. The phase III lots maybe considered as not clinically different as statistical equivalence was shown for serotypes 1, 3 and 4across the phase III lots. For serotype 2, although equivalence was not shown between two lots, the GMTsobserved in the phase III lots were consistently higher than those for the phase II lot. As such, in our view,biological equivalence for all serotypes was demonstrated.Joseph Torresi, Leon G. Heron, Ming Qiao, Joanne Marjason, Laurent Chambonneau, Alain Bouckenooghe, Mark Boaz, Diane van der Vliet, Derek Wallace, Yanee Hutagalung, Michael D. Nissen, Peter C. Richmon
Reaction dynamics induced by the radioactive ion beam 7Be on medium-mass and heavy targets
We studied the reaction dynamics induced at Coulomb barrier energies by the weakly-bound Radioactive Ion Beam 7Be (Sα = 1.586 MeV) on medium-mass (58Ni) and heavy (208Pb) targets. The experiments were performed at INFN-LNL (Italy), where a 2-3×105 pps 7Be secondary beam was produced with the RIB in-flight facility EXOTIC. Charged reaction products were detected by means of high-granularity silicon detectors in rather wide angular ranges. The contribution presents an up-to-date status of the data analysis and theoretical interpretation for both systems.European Commission, Seventh Framework Programme 60037
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