657 research outputs found
Auditory affective processing requires awareness
Recent work has challenged the previously widely accepted belief that affective processing does not require awareness and can be carried out with more limited resources than semantic processing. This debate has focused exclusively on visual perception, even though evidence from both human and animal studies suggests that existence for nonconscious affective processing would be physiologically more feasible in the auditory system. Here we contrast affective and semantic processing of nonverbal emotional vocalizations under different levels of awareness in three experiments, using explicit (two-alternative forced choice masked affective and semantic categorization tasks, Experiments 1 and 2) and implicit (masked affective and semantic priming, Experiment 3) measures. Identical stimuli and design were used in the semantic and affective tasks. Awareness was manipulated by altering stimulus-mask signal-to-noise ratio during continuous auditory masking. Stimulus awareness was measured on each trial using a four-point perceptual awareness scale. In explicit tasks, neither affective nor semantic categorization could be performed in the complete absence of awareness, while both tasks could be performed above chance level when stimuli were consciously perceived. Semantic categorization was faster than affective evaluation. When the stimuli were partially perceived, semantic categorization accuracy exceeded affective evaluation accuracy. In implicit tasks neither affective nor semantic priming occurred in the complete absence of awareness, whereas both affective and semantic priming emerged when participants were aware of the primes. We conclude that auditory semantic processing is faster than affective processing, and that both affective and semantic auditory processing are dependent on awareness
Physical parameters of a relativistic jet at very high redshift: the case of the blazar J1430+4204
Context. The high-redshift (z = 4.72) blazar J1430+4204 produced a major
radio outburst in 2005. Such outbursts are usually associated with the
emergence of a new component in the inner radio jet. Aims. We searched for
possible changes in the radio structure on milli-arcsecond angular scales, to
determine physical parameters that characterise the relativistic jet ejected
from the centre of this source. Methods. We analysed 15-GHz radio
interferometric images obtained with the Very Long Baseline Array (VLBA) before
and after the peak of the outburst. Results. We did not identify any
significant new jet component over a period of 569 days. We estimated the
Doppler factor, the Lorentz factor, and the apparent transverse speed of a
putative jet component using three different methods. The likely small jet
angle to the line of sight and our values of the apparent transverse speed are
consistent with not detecting a new jet feature.Comment: (6 pages, 4 figures) accepted for publication in Astronomy and
Astrophysic
37 GHz observations of narrow-line Seyfert 1 galaxies
Observations at 37 GHz, performed at Mets\"ahovi Radio Observatory, are
presented for a sample of 78 radio-loud and radio-quiet narrow-line Seyfert 1
(NLS1) galaxies, together with additional lower and higher frequency radio data
from RATAN-600, Owens Valley Radio Observatory, and the Planck satellite. Most
of the data have been gathered between February 2012 and April 2015 but for
some sources even longer lightcurves exist. The detection rate at 37 GHz is
around 19%, comparable to other populations of active galactic nuclei presumed
to be faint at radio frequencies, such as BL Lac objects. Variability and
spectral indices are determined for sources with enough detections. Based on
the radio data, many NLS1 galaxies show a blazar-like radio spectra exhibiting
significant variability. The spectra at a given time are often inverted or
convex. The source of the high-frequency radio emission in NLS1 galaxies,
detected at 37 GHz, is most probably a relativistic jet rather than star
formation. Jets in NLS1 galaxies are therefore expected to be a much more
common phenomenon than earlier assumed.Comment: Accepted for publication in A&A. Table of 37 GHz data will be
available at the CDS soo
Broad-band properties of flat-spectrum radio-loud narrow-line Seyfert 1 galaxies
We report about recent updates of broad-band properties of radio-loud
narrow-line Seyfert 1 galaxies.Comment: 5 pages, no figures. Proceedings 28th Texas Symposium on Relativistic
Astrophysics, Geneva (Switzerland), 13-18 December 201
A multifrequency analysis of radio variability of blazars
We have carried out a multifrequency analysis of the radio variability of
blazars, exploiting the data obtained during the extensive monitoring programs
carried out at the University of Michigan Radio Astronomy Observatory (UMRAO,
at 4.8, 8, and 14.5 GHz) and at the Metsahovi Radio Observatory (22 and 37
GHz). Two different techniques detect, in the Metsahovi light curves, evidences
of periodicity at both frequencies for 5 sources (0224+671, 0945+408, 1226+023,
2200+420, and 2251+158). For the last three sources consistent periods are
found also at the three UMRAO frequencies and the Scargle (1982) method yields
an extremely low false-alarm probability. On the other hand, the 22 and 37 GHz
periodicities of 0224+671 and 0945+408 (which were less extensively monitored
at Metsahovi and for which we get a significant false-alarm probability) are
not confirmed by the UMRAO database, where some indications of ill-defined
periods about a factor of two longer are retrieved. We have also investigated
the variability index, the structure function, and the distribution of
intensity variations of the most extensively monitored sources. We find a
statistically significant difference in the distribution of the variability
index for BL Lac objects compared to flat-spectrum radio quasars (FSRQs), in
the sense that the former objects are more variable. For both populations the
variability index steadily increases with increasing frequency. The
distribution of intensity variations also broadens with increasing frequency,
and approaches a log-normal shape at the highest frequencies. We find that
variability enhances by 20-30% the high frequency counts of extragalactic
radio-sources at bright flux densities, such as those of the WMAP and Planck
surveys.Comment: A&A accepted. 12 pages, 16 figure
The milliarcsecond-scale jet of PKS 0735+178 during quiescence
We present polarimetric 5 GHz to 43 GHz VLBI observations of the BL Lacertae
object PKS 0735+178, spanning March 1996 to May 2000. Comparison with previous
and later observations suggests that the overall kinematic and structural
properties of the jet are greatly influenced by its activity. Time intervals of
enhanced activity, as reported before 1993 and after 2000 by other studies, are
followed by highly superluminal motion along a rectilinear jet. In contrast the
less active state in which we performed our observations, shows subluminal or
slow superluminal jet features propagating through a twisted jet with two sharp
bends of about 90 deg. within the innermost three-milliarcsecond jet structure.
Proper motion estimates from the data presented here allow us to constrain the
jet viewing angle to values < 9 deg., and the bulk Lorentz factor to be between
2 and 4.Comment: 11 pages, 12 figures. Accepted for publication in A&
Testing the blazar spectral sequence: X-ray selected blazars
We present simultaneous optical and X-ray data from Swift for a sample of
FSRQs selected from the EMSS survey. We present also a complete analysis of
Swift and INTEGRAL data on 4 blazars recently discussed as possibly challenging
the trends of the "blazar spectral sequence". The SEDs of all these objects are
modelled in terms of a general theoretical scheme leading to an estimate of the
jets' physical parameters. Our results show that, in the case of the EMSS broad
line blazars, X-ray selection does not lead to find sources with synchrotron
peaks in the UV/X-ray range, as was the case for X-ray selected BL Lacs.
Instead, for a wide range of radio powers all the sources with broad emission
lines show similar SEDs, with synchrotron components peaking below the
optical/UV range. Of the remaining 4 "anomalous" blazars, two highly luminous
sources with broad lines, claimed to possibly emit synchrotron X-rays, are
shown to be better described with IC models for their X-ray emission. For one
source with weak emission lines (a BL Lac object) a synchrotron peak in the
soft X-ray range is confirmed, while for the fourth source, exhibiting lines
typical of NLSy1s, no evidence of X-ray emission from a relativistic jet is
found. We reexamine the original "blazar spectral sequence" and suggest that
the photon ambient, in which the particle acceleration and emission occur, is
likely the main factor determining the shape of the blazar SED.Comment: 11 figures and 6 tables. Accepted for publication in MNRA
A historic jet-emission minimum reveals hidden spectral features in 3C 273
Aims. The aim of this work is to identify and study spectral features in the
quasar 3C 273 usually blended by its strong jet emission. Method. A historic
minimum in the sub-millimetre emission of 3C 273 triggered coordinated
multi-wavelength observations in June 2004. X-ray observations from the
INTEGRAL, XMM-Newton and RXTE satellites are complemented by ground-based
optical, infrared, millimetre and radio observations. The overall spectrum is
used to model the infrared and X-ray spectral components. Results. Three
thermal dust emission components are identified in the infrared. The dust
emission on scales from 1 pc to several kpc is comparable to that of other
quasars, as expected by AGN unification schemes. The observed weakness of the
X-ray emission supports the hypothesis of a synchrotron self-Compton origin for
the jet component. There is a clear soft-excess and we find evidence for a very
broad iron line which could be emitted in a disk around a Kerr black hole.
Other signatures of a Seyfert-like X-ray component are not detected.Comment: 4 pages. Accepted for publication in A&A Letter
Understanding the impact of legislation on 'reduction of disease risk' claims on food and drinks: The REDICLAIM project
The Nutrition and Health Claims Regulation (EC No. 1924/2006) has established a common framework for the regulation of nutrition and health claims used on foods across the European Union. This regulation aims to provide the European food industry opportunities for product innovation whilst protecting consumer interests with respect to controlling misleading advertising and promoting public health. However, in order to satisfy the approval of new health claims procedure particularly for new 'reduction of disease risk' claims [Article 14(1)(a) claims], significant research activity is required by industry to scientifically substantiate the claims they wish to make. There is a need to establish whether the implementation of this legislation is in fact driving product innovation and the development of healthy foods or whether it forms a barrier to such developments. The EU-funded REDICLAIM project is currently considering these issues. This article describes the project's preliminary results and outlines the further programme of work
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