1,360 research outputs found
Into the realm of social capital for adolescents: a latent profile analysis
Background Recent reports of increasing prevalence of frequent health complaints and mental health problems among adolescents call for directing more attention on determinants of adolescent health. The relationship between health and social capital has gained increased attention since the early 2000’s and research at review level confirms the importance of social capital for health outcomes, despite methodological heterogeneity. The aim of this study was to identify distinct profiles of family, school and peer social capital in a nationally representative sample of adolescents and to explore health outcomes in those profiles. Method Cross-sectional data from the Swedish Health Behaviour of School-aged Children 2013/14 was used for this study. The analytical sample consisted of 7,804 adolescents aged 11-, 13- and 15-years. Items representing sense of belonging and emotional support were assessed in three contexts; family, school and among peers. Latent profile analyses (LPA) were run to determine social capital profiles. Health outcomes included frequent health complaints and life satisfaction, while socioeconomic status and genders were included as predictors. Results The results show that five distinct profiles best represent the data for 11- and 15-year olds, while a four-profile model was optimal for 13-year olds. Some profiles were recurrent between age groups but unique profiles were also found. Health outcomes were significantly different between profiles depending on levels of social capital in the different contexts. Conclusions This study provides novel insight into how social capital co-occurs among adolescents within the contexts of family, school and peers and how this translates into differences in health outcomes. The national representativeness of the sample increases the implications of the results and contributes to meaningful insights that help explain the interactions of social capital in multiple contexts, complementing what is previously known about the relationship with adolescent health. © 2019 Ahlborg 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
Metallicity at the explosion sites of interacting transients
Context. Some circumstellar-interacting (CSI) supernovae (SNe) are produced
by the explosions of massive stars that have lost mass shortly before the SN
explosion. There is evidence that the precursors of some SNe IIn were luminous
blue variable (LBV) stars. For a small number of CSI SNe, outbursts have been
observed before the SN explosion. Eruptive events of massive stars are named as
SN impostors (SN IMs) and whether they herald a forthcoming SN or not is still
unclear. The large variety of observational properties of CSI SNe suggests the
existence of other progenitors, such as red supergiant (RSG) stars with
superwinds. Furthermore, the role of metallicity in the mass loss of CSI SN
progenitors is still largely unexplored. Aims. Our goal is to gain insight on
the nature of the progenitor stars of CSI SNe by studying their environments,
in particular the metallicity at their locations. Methods. We obtain
metallicity measurements at the location of 60 transients (including SNe IIn,
SNe Ibn, and SN IMs), via emission-line diagnostic on optical spectra obtained
at the Nordic Optical Telescope and through public archives. Metallicity values
from the literature complement our sample. We compare the metallicity
distributions among the different CSI SN subtypes and to those of other
core-collapse SN types. We also search for possible correlations between
metallicity and CSI SN observational properties. Results. We find that SN IMs
tend to occur in environments with lower metallicity than those of SNe IIn.
Among SNe IIn, SN IIn-L(1998S-like) SNe show higher metallicities, similar to
those of SNe IIL/P, whereas long-lasting SNe IIn (1988Z-like) show lower
metallicities, similar to those of SN IMs. The metallicity distribution of SNe
IIn can be reproduced by combining the metallicity distributions of SN IMs
(that may be produced by major outbursts of massive stars like LBVs) and SNe
IIP (produced by RSGs). The same applies to the distributions of the Normalized
Cumulative Rank (NCR) values, which quantifies the SN association to H II
regions. For SNe IIn, we find larger mass-loss rates and higher CSM velocities
at higher metallicities. The luminosity increment in the optical bands during
SN IM outbursts tend to be larger at higher metallicity, whereas the SN IM
quiescent optical luminosities tend to be lower. Conclusions. The difference in
metallicity between SNe IIn and SN IMs suggests that LBVs are only one of the
progenitor channels for SNe IIn, with 1988Z-like and 1998S-like SNe possibly
arising from LBVs and RSGs, respectively. Finally, even though linedriven winds
likely do not primarily drive the late mass-loss of CSI SN progenitors,
metallicity has some impact on the observational properties of these
transients. Key words. supernovae: general - stars: evolution - galaxies:
abundancesComment: Submitted to Astronomy and Astrophysics on 28/02/2015; submitted to
arXiv after the 1st referee repor
Prediction of Indigestible NDF Content of Grass and Legume Silages by NIRS
The future feed evaluation systems based on mechanistic digestion models require reliable estimates of forage digestible and indigestible NDF content (DNDF and INDF). The objective of this study was to examine the potential of near infrared reflectance spectroscopy (NIRS) in predicting INDF content of grass and legume silages
No trace of a single-degenerate companion in late spectra of SNe 2011fe and 2014J
Left-over, ablated material from a possible non-degenerate companion can
reveal itself after about one year in spectra of Type Ia SNe (SNe Ia). We have
searched for such material in spectra of SN 2011fe (at 294 days after the
explosion) and for SN 2014J (315 days past explosion). The observations are
compared with numerical models simulating the expected line emission. The
spectral lines sought for are H-alpha, [O I] 6300 and [Ca II] 7291,7324, and
the expected width of these lines is about 1000 km/s. No signs of these lines
can be traced in any of the two supernovae. When systematic uncertainties are
included, the limits on hydrogen-rich ablated gas in SNe 2011fe and 2014J are
0.003 M_sun and 0.0085 M_sun, respectively, where the limit for SN 2014J is the
second lowest ever, and the limit for SN 2011fe is a revision of a previous
limit. Limits are also put on helium-rich ablated gas. These limits are used,
in conjunction with other data, to argue that these supernovae can stem from
double-degenerate systems, or from single-degenerate systems with a spun
up/spun down super-Chandrasekhar white dwarf. For SN 2011fe, other types of
hydrogen-rich donors can likely be ruled out, whereas for SN 2014J a
main-sequence donor system with large intrinsic separation is still possible.
Helium-rich donor systems cannot be ruled out for any of the two supernovae,
but the expected short delay time for such progenitors makes this possibility
less likely, especially for SN 2011fe. The broad [Ni II] 7378 emission in SN
2014J is redshifted by about +1300 km/s, as opposed to the known blueshift of
roughly -1100 km/s for SN 2011fe. [Fe II] 7155 is also redshifted in SN 2014J.
SN 2014J belongs to a minority of SNe Ia that both have a nebular redshift of
[Fe II] 7155 and [Ni II] 7378, and a slow decline of the Si II 6355 absorption
trough just after B-band maximum.Comment: 13 pages, submitted to A&
PO-0958: Correlations between DCE-MRI, [18F]-FLT PET and survival in patients with high grade glioma
The bumpy light curve of supernova iPTF13z
A Type IIn supernova (SN) is dominated by the interaction of SN ejecta with
the circumstellar medium (CSM). Some SNe IIn (e.g., SN 2006jd) have episodes of
re-brightening ("bumps") in their light curves. We present iPTF13z, a SN IIn
discovered by the intermediate Palomar Transient Factory (iPTF) and
characterised by several bumps in its light curve. We analyse this peculiar
behaviour trying to infer the properties of the CSM and of the SN explosion, as
well as the nature of its progenitor star. We obtained multi-band optical
photometry for over 1000 days after discovery with the P48 and P60 telescopes
at Palomar Observatory. We obtained low-resolution optical spectra in the same
period. We did an archival search for progenitor outbursts. We analyse our
photometry and spectra, and compare iPTF13z to other SNe IIn. A simple
analytical model is used to estimate properties of the CSM. iPTF13z was a SN
IIn showing a light curve with five bumps during its decline phase. The bumps
had amplitudes between 0.4 and 0.9 mag and durations between 20 and 120 days.
The most prominent bumps appeared in all our different optical bands. The
spectra showed typical SN IIn characteristics, with emission lines of H
(with broad component FWHM ~ and narrow
component FWHM ~) and He I, but also with Fe II, Ca II,
Na I D and H P-Cygni profiles (with velocities of ~ ). A pre-explosion outburst was identified lasting days,
with mag around 210 days before discovery. Large, variable
progenitor mass-loss rates (~> 0.01 ) and CSM densities
(~> 10 g cm) are derived. We suggest that the light curve bumps
of iPTF13z arose from SN ejecta interacting with denser regions in the CSM,
possibly produced by the eruptions of a luminous blue variable star.Comment: Version 2: Update to match published paper. 21 pages, 14 figures,
abstract abridged to comply with arXiv length limit. In version 1 of the
paper on arXiv, Table 3 had some erroneous entries. Table 3 is now corrected
and available via VizieR. Version 1 comment: Accepted for publication in
Astronomy & Astrophysics (24 pages, 14 figures, abstract abridged by 20 % not
to exceed the arXiv length limit
Unified Behavior of Alkali Core-Level Binding-Energy Shifts Induced by sp Metals
Thin overlayers of Na, K, Rb, and Cs on different sp-metal substrates have been investigated using photoelectron spectroscopy. The alkali core levels show clearly resolved binding-energy shifts between the surface layer, the intermediate layer(s), and the interface layer. The magnitude of these shifts depends on sp metal and on alkali metal. The layer-resolved core-level binding-energy shifts are well reproduced by models based on a thermodynamical description. For three-layer alkali films the core-level binding energy of the intermediate layer is found to exhibit a small but significant shift between different sp-metal substrates. A simple relationship between the core-level binding-energy shift for the interface layer and the difference in rs value between the sp substrate and the adsorbate is shown to exist
Compuestos de fosfito de trialilo con iones metálicos de configuración d8
All the attempts to prepare complexes of triallyI phosphite with Pt (II)
were unsuccessful. However, the reactions of this ligand with Rh (1) and
Pd (II) ,take place and synthesis condi.tions are described. The composition
and nature of the insulated complexes was elucid·ated by elemental analysis,
molecular weight measurements and infrared and nuclear magnetic resonanse data.
The triallylphosphite reaction with RhCI goes to the synthesis of chloro
(triallylphosphite) rhodium (1), with all the olefin groups coordinated to the
rhodium, but with Rh el (PPh3) the trans-chlorocarbonYI bis (Triphenylphosphine) rhodium (1) is insulated. On the other hand, equivalen,t amounts
of (CfiH5CN)2PdCI and ligand react ,to g:ve bisallyldi-f
L--chloropalladium (Il).Láboratorios William Ramsay y Ralph Forster del University College London (Inglaterra)
Artturi Assists Finnish Advisers and Farmers to Succeed in Grass-Based Dairy Production
Artturi is a collective name for a wide range of services. It is a common tool for different bodies who share an interest in strengthening grass-based dairy production in Finland: research, advisory service and industries. The Service is named after A. I. (Artturi Ilmari) Virtanen, the Finnish scientist who was awarded the Nobel prize in 1945, partly based on his work in developing the ensiling process of grass. The Artturi web site is available in Internet at: http://www.agronet.fi/artturi. Access to Artturi Services is free and no registration is required. The language used is Finnish. During summer 2003, 15,000 visits were recorded at the web site
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