9,223 research outputs found
Stars and brown dwarfs in the sigma Orionis cluster. III. OSIRIS/GTC low-resolution spectroscopy of variable sources
Context. Although many studies have been performed so far, there are still
dozens of low-mass stars and brown dwarfs in the young sigma Orionis open
cluster without detailed spectroscopic characterisation. Aims. We look for
unknown strong accretors and disc hosts that were undetected in previous
surveys. Methods. We collected low-resolution spectroscopy (R ~ 700) of ten
low-mass stars and brown dwarfs in sigma Orionis with OSIRIS at the Gran
Telescopio Canarias under very poor weather conditions. These objects display
variability in the optical, infrared, Halpha, and/or X-rays on time scales of
hours to years. We complemented our spectra with optical and near-/mid-infrared
photometry. Results. For seven targets, we detected lithium in absorption,
identified Halpha, the calcium doublet, and forbidden lines in emission, and/or
determined spectral types for the first time. We characterise in detail a
faint, T Tauri-like brown dwarf with an 18 h-period variability in the optical
and a large Halpha equivalent width of -125+/-15 AA, as well as two M1-type,
X-ray-flaring, low-mass stars, one with a warm disc and forbidden emission
lines, the other with a previously unknown cold disc with a large inner hole.
Conclusions. New unrevealed strong accretors and disc hosts, even below the
substellar limit, await discovery among the list of known sigma Orionis stars
and brown dwarfs that are variable in the optical and have no detailed
spectroscopic characterisation yet.Comment: A&A, in press (accepted for publication in section 14. Catalogs and
data of Astronomy and Astrophysics
Epidemiology of Kidney Cancer
Some tumors are known to have a definite cause-effect etiology, but renal cell carcinoma (RCC) is not one of them precisely. With regard to RCC we can only try to identify some clinical and occupational factors as well as substances related to tumorigenesis. Smoking, chemical carcinogens like asbestos or organic solvents are some of these factors that increase the risk of the RCC. Viral infections and radiation therapy have also been described as risk factors. Some drugs can increase the incidence of RCC as well as other neoplasms. Of course, genetics plays an outstanding role in the development of some cases of kidney cancer. Chronic renal failure, hypertension, and dialysis need to be considered as special situations. Diet, obesity, lifestyle, and habits can also increase the risk of RCC. The aim of this review is to summarize the well-defined causes of renal cell carcinoma
Predictive learning, prediction errors, and attention: evidence from event-related potentials and eye tracking
Prediction error (‘‘surprise’’) affects the rate of learning: We learn more rapidly about cues for which we initially make incorrect predictions than cues for which our initial predictions are correct. The current studies employ electrophysiological measures to reveal early attentional differentiation of events that differ in their previous involvement in errors of predictive judgment.
Error-related events attract more attention, as evidenced by features of event-related scalp potentials previously implicated in selective visual attention (selection negativity, augmented anterior N1). The earliest differences detected occurred around 120 msec after stimulus onset, and distributed source localization (LORETA)
indicated that the inferior temporal regions were one source of the earliest differences. In addition, stimuli associated with the production of prediction errors show higher dwell times in an eyetracking procedure. Our data support the view that early attentional processes play a role in human associative learning
Field experimental study of traffic-induced turbulence on highways
This paper is focused on traffic-induced turbulence (TIT) analysis from a field campaign performed in 2011, using ultrasonic anemometers deployed in the M-12 Highways, Madrid (Spain). The study attempts to improve knowledge about the influence of traffic-related parameters on turbulence. Linear relationships between vehicle speed and turbulent kinetic energy (TKE) values are found with coefficients of determination (R2) of 0.75 and 0.55 for the lorry and van respectively. The vehicle-induced fluctuations in the wind components (u', v' and w') showed the highest values for the longitudinal component (v) because of the wake-passing effect. In the analysis of wake produced by moving vehicles it is indicated how the turbulence dissipates in relation to a distance d and height h. The TKE values were found to be higher at the measuring points closer to the surface during the wake analysis.This work was supported by the OASIS Research Project that was co financed by CDTI (Spanish Science and Innovation Ministry) and developed with the Spanish companies: Iridium, OHL Concesiones, Abertis, Sice, Indra, Dragados, OHL, Geocisa, GMV, Asfaltos Augusta, Hidrofersa, Eipsa, PyG, CPS, AEC and Torre de Comares Arquitectos s.l and 16 research centres
Unconventional spin texture of a topologically nontrivial semimetal Sb(110)
The surfaces of antimony are characterized by the presence of spin-split
states within the projected bulk band gap and the Fermi contour is thus
expected to exhibit a spin texture. Using spin-resolved density functional
theory calculations, we determine the spin polarization of the surface bands of
Sb(110). The existence of the unconventional spin texture is corroborated by
the investigations of the electron scattering on this surface. The charge
interference patterns formed around single scattering impurities, imaged by
scanning tunneling microscopy, reveal the absence of direct backscattering
signal. We identify the allowed scattering vectors and analyze their bias
evolution in relation to the surface-state dispersion.Comment: 10 pages, 5 figure
The neural correlates of subjectively perceived and passively matched loudness perception in auditory phantom perception
International audienceIntroduction: A fundamental question in phantom perception is determining whether the brain creates a network that represents the sound intensity of the auditory phantom as measured by tinnitus matching (in dB), or whether the phantom perception is actually only a representation of the subjectively perceived loudness. Methods: In tinnitus patients, tinnitus loudness was tested in two ways, by a numeric rating scale for subjectively perceived loudness and a more objective tinnitus-matching test, albeit it is still a subjective measure. Results: Passively matched tinnitus does not correlate with subjective numeric rating scale, and has no electrophysiological correlates. Subjective loudness, in a whole-brain analysis, is correlated with activity in the left anterior insula (alpha), the rostral/dorsal anterior cingulate cortex (beta), and the left parahip-pocampus (gamma). A ROI analysis finds correlations with the auditory cortex (high beta and gamma) as well. The theta band links gamma band activity in the auditory cortex and parahippocampus via theta–gamma nesting. Conclusions: Apparently the brain generates a network that represents subjectively perceived tinnitus loudness only, which is context dependent. The subjective loudness network consists of the anterior cingulate/insula, the parahippocam-pus, and the auditory cortex. The gamma band activity in the parahippocampus and the auditory cortex is functionally linked via theta–gamma nested lagged phase synchronization
When stereotype threat does not impair performance, self-affirmation can be harmful
International audienc
Teegi: Tangible EEG Interface
We introduce Teegi, a Tangible ElectroEncephaloGraphy (EEG) Interface that
enables novice users to get to know more about something as complex as brain
signals, in an easy, en- gaging and informative way. To this end, we have
designed a new system based on a unique combination of spatial aug- mented
reality, tangible interaction and real-time neurotech- nologies. With Teegi, a
user can visualize and analyze his or her own brain activity in real-time, on a
tangible character that can be easily manipulated, and with which it is
possible to interact. An exploration study has shown that interacting with
Teegi seems to be easy, motivating, reliable and infor- mative. Overall, this
suggests that Teegi is a promising and relevant training and mediation tool for
the general public.Comment: to appear in UIST-ACM User Interface Software and Technology
Symposium, Oct 2014, Honolulu, United State
The role of dieting, happiness with appearance, self-esteem, and bullying in the relationship between mental health and body-mass index among UK adolescents: a longitudinal analysis of the Millennium Cohort Study.
BACKGROUND: Mental illness and obesity are among the biggest challenges to population health, they are linked, and may be modifiable during adolescence. We aimed to determine intervening pathways between mental health and BMI z-score symptoms across adolescence. METHODS: In this longitudinal cohort study, we used path models to examine self-reported dieting, happiness with appearance, self-esteem and bullying at 14 years as potential mediators of the cross-lagged relationship between mental health (via the Strengths and Difficulties Questionnaire) and Body Mass Index (BMI) z-score at 11 and 17 years by sex in the UK Millennium Cohort Study, a prospective cohort study of 18,818 children born in the UK between September 1st, 2000, and January 31st, 2002. Full, incomplete data on all singleton children still participating in the study by age 11 years were analysed in GSEM via maximum likelihood estimation (N = 12,450). FINDINGS: We found happiness with appearance and self-esteem, but not dieting or bullying, mediated the relationship between BMI age 11 and mental health age 17. Each increase in BMI z-score at 11 years was associated with 0.12 increase for boys and a 0.19 increase for girls in scores of unhappiness with appearance (boys: b 0.12, 95% C.I.; girls b 0.19, C.I. 0.14 to 0.23) and a 16% increase for boys and a 22% increase for girls in odds of low self-esteem (boys OR 1.16, 95% C.I. 1.07 to 1.26; girls: OR 1.22, 95% C.I. 1.15 to 1.30) at 14 years. In turn, for both boys and girls, being unhappy with appearance and low self-esteem at 14 years were associated with a greater likelihood of emotional and externalizing symptoms at 17 years. INTERPRETATION: Early prevention strategies to encourage healthy physical and mental development of children need to focus on the promotion of positive body-mage and self-esteem. FUNDING: The National Institute for Health and Care Research (NIHR) School for Public Health Research (SPHR)
A high Eddington-ratio, true Seyfert 2 galaxy candidate: implications for broad-line-region models
A bright, soft X-ray source was detected on 2010 July 14 during an
XMM--Newton slew at a position consistent with the galaxy GSN 069 (z=0.018).
Previous ROSAT observations failed to detect the source and imply that GSN 069
is now >240 times brighter than it was in 1994 in the soft X-ray band. We
report here results from a ~1 yr monitoring with Swift and XMM-Newton, as well
as from optical spectroscopy. GSN 069 is an unabsorbed, ultra-soft source in
X-rays, with no flux detected above ~1 keV. The soft X-rays exhibit significant
variability down to timescales of hundreds of seconds. The UV-to-X-ray spectrum
of GSN 069 is consistent with a pure accretion disc model which implies an
Eddington ratio of ~0.5 and a black hole mass of ~ 1.2 million solar masses. A
new optical spectrum, obtained ~3.5 months after the XMM-Newton slew detection,
is consistent with earlier spectra and lacks any broad line component,
classifying the source as a Seyfert 2 galaxy. The lack of cold X-ray absorption
and the short timescale variability in the soft X-rays rule out a standard
Seyfert 2 interpretation of the X-ray data. We discuss our results within the
framework of two possible scenarios for the broad-line-region (BLR) in AGN,
namely the two-phase model (cold BLR clouds in pressure equilibrium with a
hotter medium), and models in which the BLR is part of an outflow, or
disc-wind. Finally, we point out that GSN 069 may be a member of a population
of super-soft AGN whose SED is completely dominated by accretion disc emission,
as it is the case in some black hole X-ray binary transients during their
outburst evolution. The disc emission for a typical AGN with larger black hole
mass than GSN 069 does not enters the soft X-ray band, so that GSN 069-like
objects would likely be missed by current X-ray surveys, or mis-classified as
Compton-thick candidates. (ABRIDGED)Comment: Accepted for publication in MNRA
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