2,194 research outputs found
Normative perceptual estimates for 91 healthy subjects age 60–75: impact of age, education, employment, physical exercise, alcohol, and video gaming
Visual perception serves as the basis for much of the higher level cognitive processing as well as human activity in general. Here we present normative estimates for the following components of visual perception: the visual perceptual threshold, the visual short-term memory capacity and the visual perceptual encoding/decoding speed (processing speed) of Visual Short-Term Memory (VSTM) based on an assessment of 91 healthy subjects aged 60-75. The estimates were modelled from input from a whole-report assessment based on A Theory of Visual Attention (TVA). In addition to the estimates themselves, we present correlational data, and multiple regression analyses between the estimates and self-reported demographic data and lifestyle variables. The regression statistics suggest that education level, video gaming activity and employment status may significantly impact the encoding/decoding speed of VTSM but not the capacity of VSTM nor the visual perceptual threshold. The estimates will be useful for future studies into the effects of various types of intervention and training on cognition in general and visual attention in particular
Chandra and RXTE spectroscopy of the accreting msec pulsar IGR J00291+5934
We report on an observation of the recently discovered accreting millisecond X-ray pulsar IGR J00291+5934 performed with the RXTE-Proportional Counter Array (PCA) and Chandra-High Energy Transmission Grating Spectrometer (HETGS). The RXTE data are from a twoweek follow-up of the source, while the Chandra observation took place around the end of the follow-up, about 12 days after the discovery of
the source, when the source flux had decreased already by a factor of ten. The analysis of the Chandra data allowed us to extract the most precise X-ray position of IGR J00291+5934, RA = 00h 29m 03.08s, and Dec =+59◦ 34 19.2 (0.6 error), compatible with the optical and radio ones.
We find that the spectra of IGR J00291+5934 can be described by a combination of a thermal component and a power-law. Along the outburst detected by PCA, the power-law photon index showed no particular trend, while the thermal component (∼1 keV, interpreted as a hot spot on
the neutron star surface) became weaker until non-detection. In the simultaneous observation of the weak Chandra /RXTE spectrum, there was no longer any indication of the ∼1 keV thermal component, while we detected a colder thermal component (∼0.4 keV) that we interpret as the
emission from the cold disc. A hint of a 6.4 keV iron line was detected, together with an excess around 6.8 keV and absorption feature around 7.1 keV. The last two features have never been detected in the spectra of accretion-driven millisecond pulsars before and, if confirmed, would
suggest the presence of an expanding hot corona with high outflow velocities
Suzaku observation of IGR J16318-4848
We report on the first Suzaku observation of IGR J16318-4848, the most
extreme example of a new group of highly absorbed X-ray binaries that have
recently been discovered by the International Gamma-Ray Astrophysics Laboratory
INTEGRAL. The Suzaku observation was carried out between 2006 August 14 and 17,
with a net exposure time of 97 ks.
The average X-ray spectrum of the source can be well described with a
continuum model typical for neutron stars i.e., a strongly absorbed power law
continuum with a photon index of 0.676(42) and an exponential cutoff at 20.5(6)
keV. The absorbing column is 1.95(3)x10e24 cm-2. Consistent with earlier work,
strong fluorescent emission lines of Fe Kalpha, Fe Kbeta, and Ni Kalpha are
observed. Despite the large absorbing column, no Compton shoulder is seen in
the lines, arguing for a non-spherical and inhomogeneous absorber.
Seen at an average 5-60 keV absorbed flux of 3.4x10e-10 erg cm-2 s-1, the
source exhibits significant variability on timescales of hours.Comment: 5 pages, 5 figures, 1 table. Accepted for publication in A&
The Effects of Iconic Gestures and Babble Language on Word Intelligibility in Sentence Context
Purpose:This study investigated to what extent iconic co-speech gestures helpword intelligibility in sentence context in two different linguistic maskers (nativevs. foreign). It was hypothesized that sentence recognition improves with thepresence of iconic co-speech gestures and with foreign compared to nativebabble.Method:Thirty-two native Dutch participants performed a Dutch word recogni-tion task in context in which they were presented with videos in which anactress uttered short Dutch sentences (e.g.,Ze begint te openen,“She starts toopen”). Participants were presented with a total of six audiovisual conditions: nobackground noise (i.e., clear condition) without gesture, no background noise withgesture, French babble without gesture, French babble with gesture, Dutch bab-ble without gesture, and Dutch babble with gesture; and they were asked to typedown what was said by the Dutch actress. The accurate identification of theaction verbs at the end of the target sentences was measured.Results:The results demonstrated that performance on the task was better inthe gesture compared to the nongesture conditions (i.e., gesture enhancementeffect). In addition, performance was better in French babble than in Dutchbabble.Conclusions:Listeners benefit from iconic co-speech gestures during commu-nication and from foreign background speech compared to native. Theseinsights into multimodal communication may be valuable to everyone whoengages in multimodal communication and especially to a public who oftenworks in public places where competing speech is present in the background
On Estimating the High-Energy Cutoff in the X-ray Spectra of Black Holes via Reflection Spectroscopy
The fundamental parameters describing the coronal spectrum of an accreting
black hole are the slope of the power-law continuum and the energy
at which it rolls over. Remarkably, this parameter can be accurately
measured for values as high as 1 MeV by modeling the spectrum of X-rays
reflected from a black hole accretion disk at energies below 100 keV. This is
possible because the details in the reflection spectrum, rich in fluorescent
lines and other atomic features, are very sensitive to the spectral shape of
the hardest coronal radiation illuminating the disk. We show that fitting
simultaneous NuSTAR (3-79 keV) and low-energy (e.g., Suzaku) data with the most
recent version of our reflection model RELXILL, one can obtain reasonable
constraints on at energies from tens of keV up to 1 MeV, for a source
as faint as 1 mCrab in a 100 ks observation.Comment: Accepted for publication in ApJL, 6 pages, 5 figure
A Suzaku, NuSTAR, and XMM-Newton view on variable absorption and relativistic reflection in NGC 4151
We disentangle X-ray disk reflection from complex line-of-sight absorption in
the nearby Seyfert NGC 4151, using a suite of Suzaku, NuSTAR, and XMM-Newton
observations. Extending upon earlier published work, we pursue a physically
motivated model using the latest angle-resolved version of the lamp-post
geometry reflection model relxillCp_lp together with a Comptonization
continuum. We use the long-look simultaneous Suzaku/NuSTAR observation to
develop a baseline model wherein we model reflected emission as a combination
of lamp-post components at the heights of 1.2 and 15.0 gravitational radii. We
argue for a vertically extended corona as opposed to two compact and distinct
primary sources. We find two neutral absorbers (one full-covering and one
partial-covering), an ionized absorber (), and a highly-ionized
ultra-fast outflow, which have all been reported previously. All analyzed
spectra are well described by this baseline model. The bulk of the spectral
variability between 1 keV and 6 keV can be accounted for by changes in the
column density of both neutral absorbers, which appear to be degenerate and
inversely correlated with the variable hard continuum component flux. We track
variability in absorption on both short (2 d) and long (1 yr) timescales;
the observed evolution is either consistent with changes in the absorber
structure (clumpy absorber at distances ranging from the broad line region
(BLR) to the inner torus or a dusty radiatively driven wind) or a geometrically
stable neutral absorber that becomes increasingly ionized at a rising flux
level. The soft X-rays below 1 keV are dominated by photoionized emission from
extended gas that may act as a warm mirror for the nuclear radiation.Comment: 21 pages, 19 figures, 8 tables, accepted for publication by A&
A Suzaku X-ray observation of one orbit of the supergiant fast X-ray transient IGR J16479-4514
We report on a 250 ks long X-ray observation of the supergiant fast X-ray
transient (SFXT) IGR J16479-4514 performed with Suzaku in 2012 February. About
80% of the short orbital period (Porb=3.32 days) was covered as continuously as
possible for the first time. The source light curve displays variability of
more than two orders of magnitude, starting with a very low emission state
lasting the first 46 ks (1E-13 erg/cm2/s, 1-10 keV), consistent with being due
to the X-ray eclipse by the supergiant companion. The transition to the
uneclipsed X-ray emission is energy dependent. Outside the eclipse, the source
spends most of the time at a level of (6-7)x10^-12 erg/cm2/s punctuated by two
structured faint flares with a duration of about 10 and 15 ks. Remarkably, the
first faint flare occurs at a similar orbital phase of the bright flares
previously observed in the system. This indicates the presence of a
phase-locked large scale structure in the supergiant wind, driving a higher
accretion rate onto the compact object. The scattered component visible during
the X-ray eclipse allowed us to directly probe the wind density at the orbital
separation, resulting in rho=7E-14 g/cm3. Assuming a spherical geometry for the
supergiant wind, the derived wind density translates into a ratio
Mdot_w/v_terminal = 7E-17 solar masses/km which, assuming terminal velocities
in a large range 500-3000 km/s, implies an accretion luminosity two orders of
magnitude higher than that observed. As a consequence, a mechanism is at work
reducing the mass accretion rate. Different possibilities are discussed.Comment: Accepted for publication in MNRAS. 10 pages, 5 figure
Transfemoral treatment for iliac occlusive disease with endoluminal stent-grafts
Objectives:Percutaneous treatment of iliac artery occlusive disease has replaced open vascular reconstruction for several indications. A balloon angioplasty with or without stent is not an option in the presence of infrainguinal extension of the disease. The authors describe a technique that allows the construction of an aorto- or iliofemoral graft through a single groin incision, using a 4 mm PTFE graft, anchoring it proximally with a Palmaz stent and dilating both to the desired diameter.Design:Retrospective non-randomised study.Materials and Methods:Nineteen procedures were performed in 16 patients mainly because of ischaemic rest pain, often with trophic skin changes or minor gangrene. Three patients had a bilateral procedure. Twelve patients had one or more associated procedures: 10 distal bypasses, one thrombectomy, one reimplantation of a distal bypass on the iliofemoral graft, one contralateral profundaplasty and two stents of the contralateral common iliac artery.Results:Two patients died, one of small bowel ischaemia and the other of a myocardial infarction. During the mean follow-up of 8.8 months, two graft thromboses occurred. In another patient bilateral stenting of a residual stenosis was necessary.Conclusions:Our experience shows that the reported technique is feasible. Whether the procedure is truly “less invasive” and the long-term results acceptable remains to be shown
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