1,161 research outputs found
HCN to HCO^+ Millimeter Line Diagnostics of AGN Molecular Torus I : Radiative Transfer Modeling
We explore millimeter line diagnostics of an obscuring molecular torus
modeled by a hydrodynamic simulation with three-dimensional nonLTE radiative
transfer calculations. Based on the results of high-resolution hydrodynamic
simulation of the molecular torus around an AGN, we calculate intensities of
HCN and HCO^{+} rotational lines as two representative high density tracers.
The three-dimensional radiative transfer calculations shed light on a
complicated excitation state in the inhomogeneous torus, even though a
spatially uniform chemical structure is assumed. Our results suggest that HCN
must be much more abundant than HCO^{+} in order to obtain a high ratio
() observed in some of the nearby galaxies. There is a
remarkable dispersion in the relation between integrated intensity and column
density, indicative of possible shortcomings of HCN(1-0) and HCO^{+}(1-0) lines
as high density tracers. The internal structures of the inhomogeneous molecular
torus down to subparsec scale in external galaxies will be revealed by the
forthcoming Atacama Large Millimeter/submillimeter Array (ALMA). The
three-dimensional radiative transfer calculations of molecular lines with
high-resolution hydrodynamic simulation prove to be a powerful tool to provide
a physical basis for molecular line diagnostics of the central regions of
external galaxies.Comment: 29 pages, 13 figures, Accepted for publication in ApJ, For high
resolution figures see http://alma.mtk.nao.ac.jp/~masako/MS72533v2.pd
The thermal state of molecular clouds in the Galactic Center: evidence for non-photon-driven heating
We used the Atacama Pathfinder Experiment (APEX) 12 m telescope to observe
the J_KaKc=3_03-2_02, 3_22-2_21, and 3_21-2_20 transitions of para-H_2CO at 218
GHz simultaneously to determine kinetic temperatures of the dense gas in the
central molecular zone (CMZ) of our Galaxy. The map extends over approximately
40 arcmin x 8 arcmin (~100x20 pc^2) along the Galactic plane with a linear
resolution of 1.2 pc. The strongest of the three lines, the H_2CO (3_03-2_02)
transition, is found to be widespread, and its emission shows a spatial
distribution similar to ammonia. The relative abundance of para-H_2CO is
0.5-1.2 10^{-9}, which is consistent with results from lower frequency H_2CO
absorption lines. Derived gas kinetic temperatures for individual molecular
clouds range from 50 K to values in excess of 100 K. While a systematic trend
toward (decreasing) kinetic temperature versus (increasing) angular distance
from the Galactic center (GC) is not found, the clouds with highest temperature
(T_kin > 100 K) are all located near the nucleus. For the molecular gas outside
the dense clouds, the average kinetic temperature is 65+/-10 K. The high
temperatures of molecular clouds on large scales in the GC region may be driven
by turbulent energy dissipation and/or cosmic-rays instead of photons. Such a
non-photon-driven thermal state of the molecular gas provides an excellent
template for the more distant vigorous starbursts found in ultraluminous
infrared galaxies (ULIRGs).Comment: 23 pages, 11 figures, A&A in pres
Canopy uptake dominates nighttime carbonyl sulfide fluxes in a boreal forest
Nighttime vegetative uptake of carbonyl sulfide (COS) can exist due to the incomplete closure of stomata and the light independence of the enzyme carbonic anhydrase, which complicates the use of COS as a tracer for gross primary productivity (GPP). In this study we derived nighttime COS fluxes in a boreal forest (the SMEAR II station in Hyytiälä, Finland; 61°51′ N, 24°17′ E; 181 m a.s.l.) from June to November 2015 using two different methods: eddy-covariance (EC) measurements (FCOS-EC) and the radon-tracer method (FCOS-Rn). The total nighttime COS fluxes averaged over the whole measurement period were −6.8 ± 2.2 and −7.9 ± 3.8 pmol m−2 s−1 for FCOS-Rn and FCOS-EC, respectively, which is 33–38 % of the average daytime fluxes and 21 % of the total daily COS uptake. The correlation of 222Rn (of which the source is the soil) with COS (average R2  =  0.58) was lower than with CO2 (0.70), suggesting that the main sink of COS is not located at the ground. These observations are supported by soil chamber measurements that show that soil contributes to only 34–40 % of the total nighttime COS uptake. We found a decrease in COS uptake with decreasing nighttime stomatal conductance and increasing vapor-pressure deficit and air temperature, driven by stomatal closure in response to a warm and dry period in August. We also discuss the effect that canopy layer mixing can have on the radon-tracer method and the sensitivity of (FCOS-EC) to atmospheric turbulence. Our results suggest that the nighttime uptake of COS is mainly driven by the tree foliage and is significant in a boreal forest, such that it needs to be taken into account when using COS as a tracer for GPP
Transition to adult care in Finnish adolescents with juvenile idiopathic arthritis
Objective The symptoms of juvenile idiopathic arthritis (JIA) and the necessity for continuous treatment may persist in adulthood. Therefore, patients with JIA need to be appropriately transferred to adult care. We aimed to analyse the timing of the patients' transition to adult care, and patients' self-management skills with the process and the quality of the transition. Method This study included 161 Finnish participants of the population-based Nordic JIA cohort who attended a 17 year follow-up appointment. Special attention was paid to the three groups: those referred by the paediatric rheumatology outpatient clinic to primary healthcare (PHC), those who were directly transferred to adult rheumatology care, and those who were later referred. Results A total of 136 patients (84%) were eligible to participate in the study, and 40% of them were directly transferred to an adult rheumatology clinic. Of the patients, 72% eventually ended up being referred to an adult rheumatology outpatient clinic. However, 16% of the patients in the PHC group had active disease during the study appointment and were referred to adult services after the study visit. Conclusion This study reveals the need to improve the transition process from paediatric care to adult care and to find the variables that can indicate the need for immediate transition. Although challenging, it is important to avoid treatment delay in adult patients with JIA who may have active disease but who do not have appropriate access to an adult rheumatological outpatient clinic.Peer reviewe
Urban aerosol number size distributions
International audienceAerosol number size distributions have been measured since 5 May 1997 in Helsinki, Finland. The presented aerosol data represents size distributions within the particle diameter size range 8-400nm during the period from May 1997 to March 2003. The daily, monthly and annual patterns of the aerosol particle number concentrations were investigated. The temporal variation of the particle number concentration showed close correlations with traffic activities. The highest total number concentrations were observed during workdays; especially on Fridays, and the lowest concentrations occurred during weekends; especially Sundays. Seasonally, the highest total number concentrations were observed during winter and spring and lower concentrations were observed during June and July. More than 80% of the number size distributions had three modes: nucleation mode (30nm), Aitken mode (20-100nm) and accumulation mode (90nm). Less than 20% of the number size distributions had either two modes or consisted of more than three modes. Two different measurement sites were used; in the first (Siltavuori, 5.5.1997-5.3.2001), the arithmetic means of the particle number concentrations were 7000cm, 6500cm, and 1000cm respectively for nucleation, Aitken, and accumulation modes. In the second site (Kumpula, 6.3.2001-28.2.2003) they were 5500cm, 4000cm, and 1000cm. The total number concentration in nucleation and Aitken modes were usually significantly higher during workdays than during weekends. The temporal variations in the accumulation mode were less pronounced. The lower concentrations at Kumpula were mainly due to building construction and also the slight overall decreasing trend during these years. During the site changing a period of simultaneous measurements over two weeks were performed showing nice correlation at both sites
Exploring the molecular chemistry and excitation in obscured luminous infrared galaxies: An ALMA mm-wave spectral scan of NGC 4418
We obtained an ALMA Cycle 0 spectral scan of the dusty LIRG NGC 4418,
spanning a total of 70.7 GHz in bands 3, 6, and 7. We use a combined local
thermal equilibrium (LTE) and non-LTE (NLTE) fit of the spectrum in order to
identify the molecular species and derive column densities and excitation
temperatures. We derive molecular abundances and compare them with other
Galactic and extragalactic sources by means of a principal component analysis.
We detect 317 emission lines from a total of 45 molecular species, including 15
isotopic substitutions and six vibrationally excited variants. Our LTE/NLTE fit
find kinetic temperatures from 20 to 350 K, and densities between 10 and
10 cm. The spectrum is dominated by vibrationally excited HCN,
HCN, and HNC, with vibrational temperatures from 300 to 450 K. We find high
abundances of HCN, SiO, HS, and c-HCCCH and a low CHOH abundance. A
principal component analysis shows that NGC 4418 and Arp 220 share very similar
molecular abundances and excitation, which clearly set them apart from other
Galactic and extragalactic environments. The similar molecular abundances
observed towards NCG 4418 and Arp 220 are consistent with a hot gas-phase
chemistry, with the relative abundances of SiO and CHOH being regulated by
shocks and X-ray driven dissociation. The bright emission from vibrationally
excited species confirms the presence of a compact IR source, with an effective
diameter 350 K. The molecular abundances
and the vibrationally excited spectrum are consistent with a young
AGN/starburst system. We suggest that NGC 4418 may be a template for a new kind
of chemistry and excitation, typical of compact obscured nuclei (CON). Because
of the narrow line widths and bright molecular emission, NGC 4418 is the ideal
target for further studies of the chemistry in CONs.Comment: accepted by A&A on 29/06/201
Detection of chloronium and measurement of the 35Cl/37Cl isotopic ratio at z=0.89 toward PKS1830-211
We report the first extragalactic detection of chloronium (H2Cl+), in the
z=0.89 absorber in front of the lensed blazar PKS1830-211. The ion is detected
through its 1_11-0_00 line along two independent lines of sight toward the
North-East and South-West images of the blazar. The relative abundance of H2Cl+
is significantly higher (by a factor ~7) in the NE line of sight, which has a
lower H2/H fraction, indicating that H2Cl+ preferably traces the diffuse gas
component. From the ratio of the H2^35Cl+ and H2^37Cl+ absorptions toward the
SW image, we measure a 35Cl/37Cl isotopic ratio of 3.1 (-0.2; +0.3) at z=0.89,
similar to that observed in the Galaxy and the solar system.Comment: Accepted for publication in A&A Lette
Probing the jet base of the blazar PKS1830-211 from the chromatic variability of its lensed images. Serendipitous ALMA observations of a strong gamma-ray flare
The launching mechanism of the jets of active galactic nuclei is
observationally poorly constrained, due to the large distances to these objects
and the very small scales (sub-parsec) involved. In order to better constrain
theoretical models, it is especially important to get information from the
region close to the physical base of the jet, where the plasma acceleration
takes place. In this paper, we report multi-epoch and multi-frequency continuum
observations of the z=2.5 blazar PKS1830-211 with ALMA, serendipitously
coincident with a strong -ray flare reported by Fermi-LAT. The blazar
is lensed by a foreground z=0.89 galaxy, with two bright images of the compact
core separated by 1". Our ALMA observations individually resolve these two
images (although not any of their substructures), and we study the change of
their relative flux ratio with time (four epochs spread over nearly three times
the time delay between the two lensed images) and frequency (between 350 and
1050 GHz, rest-frame of the blazar), during the -ray flare. In
particular, we detect a remarkable frequency-dependent behaviour of the flux
ratio, which implies the presence of a chromatic structure in the blazar (i.e.,
a core-shift effect). We rule out the possiblity of micro- and milli-lensing
effects and propose instead a simple model of plasmon ejection in the blazar's
jet to explain the time and frequency variability of the flux ratio. We suggest
that PKS1830-211 is likely one of the best sources to probe the activity at the
base of a blazar's jet at submillimeter wavelengths, thanks to the peculiar
geometry of the system. The implications of the core-shift in absorption
studies of the foreground z=0.89 galaxy (e.g., constraints on the cosmological
variations of fundamental constants) are discussed.Comment: Accepted for publication in A&
The association between cross-cultural competence and well-being among registered native and foreign-born nurses in Finland
Background A growing body of research indicates that cross-cultural competence in nurses can improve migrant patients’ health-related outcomes, but little is known about the potential benefits of cross-cultural competence on the nurses’ own well-being. Objective To examine whether cross-cultural competence (empathy, skills, positive attitudes, and motivation) is associated with perceived time pressure at work, psychological distress, and sleep problems among registered nurses in Finland, and whether there are differences in these potential associations between native and foreign-born nurses. Methods The present cross-sectional study was based on a sample of 212 foreign-born nurses licensed to practice in Finland and a random sample of 744 native Finnish nurses. Data were collected with a questionnaire and analyzed using multiple linear regression and structural equation modeling (SEM). Results Of all four dimensions of cross-cultural competence, only empathy was associated with perceived time pressure (β = –0.13, p = .018), distress (β = –0.23, p .05). Conclusions Cross-cultural empathy may protect against perceived time pressure, distress, and sleep problems in both native and foreign-born nurses. Thus, the promotion of this component of cross-cultural competence among nursing personnel should be encouraged. © 2018 Wesołowska et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Peer reviewe
On the disappearance of a cold molecular torus around the low-luminosity active galactic nucleus of NGC 1097
We used the Atacama Large Millimeter/submillimeter Array (ALMA) to map the
CO(3-2) and the underlying continuum emissions around the type 1 low-luminosity
active galactic nucleus (LLAGN; bolometric luminosity
erg~s) of NGC 1097 at pc resolution. These observations
revealed a detailed cold gas distribution within a pc of this LLAGN.
In contrast to the luminous Seyfert galaxy NGC 1068, where a pc cold
molecular torus was recently revealed, a distinctively dense and compact torus
is missing in our CO(3-2) integrated intensity map of NGC 1097. Based on the
CO(3-2) flux, the gas mass of the torus of NGC 1097 would be a factor of
less than that found for NGC 1068 by using the same CO-to-H
conversion factor, which implies less active nuclear star formation and/or
inflows in NGC 1097. Our dynamical modeling of the CO(3-2) velocity field
implies that the cold molecular gas is concentrated in a thin layer as compared
to the hot gas traced by the 2.12 m H emission in and around the
torus. Furthermore, we suggest that NGC 1097 hosts a geometrically thinner
torus than NGC 1068. Although the physical origin of the torus thickness
remains unclear, our observations support a theoretical prediction that
geometrically thick tori with high opacity will become deficient as AGNs evolve
from luminous Seyferts to LLAGNs.Comment: 9 pages, 5 figures. Accepted for publication in ApJ
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