7,350 research outputs found
Galaxy evolution across the optical emission-line diagnostic diagrams?
The discovery of the M-sigma relation, the local galaxy bimodality, and the
link between black-hole and host-galaxy properties, have raised the question
whether AGN play a role in galaxy evolution. Several theoretical models
implement AGN feedback to explain the observed galaxy luminosity function, and
possibly the color and morphological transformation of spiral galaxies into
passive ellipticals. To understand the importance of AGN feedback, a study of
the AGN populations in the radio-optical domain is crucial. A mass sequence
linking star-forming galaxies and AGN has been already noted in previous works,
and it is now investigated as possible evolutionary sequence. We observed a
sample of 119 intermediate-redshift (0.04<z<0.4) SDSS-FIRST radio emitters with
the Effelsberg 100-m telescope at 4.85 and 10.45 GHz and obtained spectral
indices. We find indications of spectral index flattening in high-metallicity
star-forming galaxies, composite galaxies, and Seyferts. This "flattening
sequence" along the [NII]-based emission-line diagnostic diagram is consistent
with the hardening of galaxy ionizing field, due to nuclear activity. After
combining our data with FIRST measurements at 1.4 GHz, we find that the
three-point radio spectra of Seyferts and LINERs show substantial differences,
attributable to small radio core components and larger (arcsecond sized)
jet/lobe components, respectively. A visual inspection of FIRST images seems to
confirm this hypothesis. Galaxies along this sequence are hypothesized to be
transitioning from the active star-forming galaxies (blue cloud) to the passive
elliptical galaxies (red sequence). This supports the suggestion that AGN play
a role in shutting down star-formation, and allow the transition from one
galaxy class to the other.Comment: 20 pages, 19 figures, accepted for publication in A&
A low-luminosity type-1 QSO sample; III. Optical spectroscopic properties and activity classification
We report on the optical spectroscopic analysis of a sample of 99
low-luminosity quasi-stellar objects (LLQSOs) at base the
Hamburg/ESO QSO survey (HES). The LLQSOs presented here offer the possibility
of studying the faint end of the QSO population at smaller cosmological
distances and, therefore, in greater detail. A small number of our LLQSO
present no broad component. Two sources show double broad components, whereas
six comply with the classic NLS1 requirements. As expected in NLR of broad line
AGNs, the [S{\sc{ii}}]based electron density values range between 100 and
1000 N/cm. Using the optical characteristics of Populations A and
B, we find that 50\% of our sources with H broad emission are consistent
with the radio-quiet sources definition. The remaining sources could be
interpreted as low-luminosity radio-loud quasar. The BPT-based classification
renders an AGN/Seyfert activity between 50 to 60\%. For the remaining sources,
the possible star burst contribution might control the LINER and HII
classification. Finally, we discuss the aperture effect as responsible for the
differences found between data sets, although variability in the BLR could play
a significant role as well.Comment: 22 pages; 5 tables; 17 figures; in press with A&
Self-sustained spatiotemporal oscillations induced by membrane-bulk coupling
We propose a novel mechanism leading to spatiotemporal oscillations in
extended systems that does not rely on local bulk instabilities. Instead,
oscillations arise from the interaction of two subsystems of different spatial
dimensionality. Specifically, we show that coupling a passive diffusive bulk of
dimension d with an excitable membrane of dimension d-1 produces a
self-sustained oscillatory behavior. An analytical explanation of the
phenomenon is provided for d=1. Moreover, in-phase and anti-phase
synchronization of oscillations are found numerically in one and two
dimensions. This novel dynamic instability could be used by biological systems
such as cells, where the dynamics on the cellular membrane is necessarily
different from that of the cytoplasmic bulk.Comment: Accepted for publication in Physical Review Letter
The Galactic centre mini-spiral in the mm-regime
The mini-spiral is a feature of the interstellar medium in the central ~2 pc
of the Galactic center. It is composed of several streamers of dust and ionised
and atomic gas with temperatures between a few 100 K to 10^4 K. There is
evidence that these streamers are related to the so-called circumnuclear disk
of molecular gas and are ionized by photons from massive, hot stars in the
central parsec. We attempt to constrain the emission mechanisms and physical
properties of the ionized gas and dust of the mini-spiral region with the help
of our multiwavelength data sets. Our observations were carried out at 1.3 mm
and 3 mm with the mm interferometric array CARMA in California in March and
April 2009, with the MIR instrument VISIR at ESO's VLT in June 2006, and the
NIR Br-gamma with VLT NACO in August 2009. We present high resolution maps of
the mini-spiral, and obtain a spectral index of 0.5 for Sgr A*, indicating an
inverted synchrotron spectrum. We find electron densities within the range
0.8-1.5x10^4 cm-3 for the mini-spiral from the radio continuum maps, along with
a dust mass contribution of ~0.25 solar masses from the MIR dust continuum, and
extinctions ranging from 1.8-3 at 2.16 micron in the Br-gamma line. We observe
a mixture of negative and positive spectral indices in our 1.3 mm and 3 mm
observations of the extended emission of the mini-spiral, which we interpret as
evidence that there are a range of contributions to the thermal free-free
emission by the ionized gas emission and by dust at 1.3 mm.Comment: 9 pages, 11 figures, accepted to A&
Zen meditation, length of telomeres, and the role of experiential avoidance and compassion
Mindfulness refers to an awareness that emerges by intentionally focusing on the present experience in a nonjudgmental or evaluative manner. Evidence regarding its efficacy has been increasing exponentially, and recent research suggests that the practice of meditation is associated with longer leukocyte telomere length. However, the psychological mechanisms underlying this potential relationship are unknown. We examined the telomere lengths of a group of 20 Zen meditation experts and another 20 healthy matched comparison participants who had not previously meditated. We also measured multiple psychological variables related to meditation practice. Genomic DNA was extracted for telomere measurement using a Life Length proprietary program. High-throughput quantitative fluorescence in situ hybridization (HT-Q-FISH) was used to measure the telomere length distribution and the median telomere length (MTL). The meditators group had a longer MTL (p = 0.005) and a lower percentage of short telomeres in individual cells (p = 0.007) than those in the comparison group. To determine which of the psychological variables contributed more to telomere maintenance, two regression analyses were conducted. In the first model, which applied to the MTL, the following three factors were significant: age, absence of experiential avoidance, and Common Humanity subscale of the Self Compassion Scale. Similarly, in the model that examined the percentage of short telomeres, the same factors were significant: age, absence of experiential avoidance, and Common Humanity subscale of the Self Compassion Scale. Although limited by a small sample size, these results suggest that the absence of experiential avoidance of negative emotions and thoughts is integral to the connection between meditation and telomeres
Burnout subtypes and absence of self-compassion in primary healthcare professionals: A cross-sectional study
Background: Primary healthcare professionals report high levels of distress and burnout. A new model of burnout has been developed to differentiate three clinical subtypes: ‘frenetic’, ‘underchallenged’ and ‘worn-out’. The aim of this study was to confirm the validity and reliability of the burnout subtype model in Spanish primary healthcare professionals, and to assess the explanatory power of the self-compassion construct as a possible protective factor.Method: The study employed a cross-sectional design. A sample of n = 440 Spanish primary healthcare professionals (214 general practitioners, 184 nurses, 42 medical residents) completed the Burnout Clinical Subtype Questionnaire (BCSQ-36), the Maslach Burnout Inventory General Survey (MBI-GS), the Self-Compassion Scale (SCS), the Utrecht Work Engagement Scale (UWES) and the Positive and Negative Affect Schedule (PANAS). The factor structure of the BCSQ-36 was estimated using confirmatory factor analysis (CFA) by the unweighted least squares method from polychoric correlations. Internal consistency (R) was assessed by squaring the correlation between the latent true variable and the observed variables. The relationships between the BCSQ-36 and the other constructs were analysed using Spearman’s r and multiple linear regression models.Results: The structure of the BCSQ-36 fit the data well, with adequate CFA indices for all the burnout subtypes. Reliability was adequate for all the scales and sub-scales (R=0.75). Self-judgement was the self-compassion factor that explained the frenetic subtype (Beta = 0.36; p<0.001); isolation explained the underchallenged (Beta = 0.16; p = 0.010); and over-identification the worn-out (Beta = 0.25; p = 0.001). Other significant associations were observed between the different burnout subtypes and the dimensions of the MBI-GS, UWES and PANAS.Conclusions: The typological definition of burnout through the BCSQ-36 showed good structure and appropriate internal consistence in Spanish primary healthcare professionals. The negative self-compassion dimensions seem to play a relevant role in explaining the burnout profiles in this population, and they should be considered when designing specific treatments and interventions tailored to the specific vulnerability of each subtype
- …