211 research outputs found
The Chemical Composition of Cernis 52 (BD+31 640)
We present an abundance analysis of the star Cernis 52 in whose spectrum we
recently reported the napthalene cation in absorption at 6707.4 {\AA}. This
star is on a line of sight to the Perseus molecular complex. The analysis of
high-resolution spectra using a chi^2-minimization procedure and a grid of
synthetic spectra provides the stellar parameters and the abundances of O, Mg,
Si, S, Ca, and Fe. The stellar parameters of this star are found to be T_{eff}
= 8350 +- 200 K, logg= 4.2 +- 0.4 dex. We derived a metallicity of [Fe/H] =
-0.01 +- 0.15. These stellar parameters are consistent with a star of
\Msun in a pre-main-sequence evolutionary stage. The stellar spectrum is
significantly veiled in the spectral range 5150-6730 {\AA} up to almost 55 per
cent of the total flux at 5150 {\AA} and decreasing towards longer wavelengths.
Using Johnson-Cousins and 2MASS photometric data, we determine a distance to
Cernis 52 of 231 pc considering the error bars of the stellar
parameters. This determination places the star at a similar distance to the
young cluster IC 348. This together with its radial velocity, v_r=13.7+-1 km/s,
its proper motion and probable young age support Cernis 52 as a likely member
of IC 348. We determine a rotational velocity of v\sin i=65 +- 5 km/s for this
star. We confirm that the stellar resonance line of \ion{Li}{1} at 6707.8 {\AA}
is unable to fit the broad feature at 6707.4 {\AA}. This feature should have a
interstellar origin and could possibly form in the dark cloud L1470 surrounding
all the cluster IC 348 at about the same distance.Comment: Accepted for publication in The Astrophysical Journa
Modulation of Circumstellar Extinction in a Young Binary System with a Low-Mass Companion in a Noncoplanar Orbit
The cyclic activity model of a young star with the low-mass secondary
component (q = M2/M1 <= 0.1) accreting a matter from circumbinary disk is
considered. It is assumed that the orbit is circular and the disk and orbital
planes are non-coplanar. Sets of hydrodynamics models of such a system have
been calculated by the SPH method and then the variations of the circumstellar
extinction and phase light curves were determined. The calculations showed that
depending on the model parameters and orientation of the system in regards to
an observer the different in shape and amplitude light curves can be observed.
An important property of the considered models is also the dependence of the
mass accretion rate onto the components on the phase of the orbital period. The
results of the calculation can be used for analysis of the cyclic activity of
UX Ori stars and young stars with the long-lasting eclipses.Comment: 14 pages, 7 figure
Seed systems smallholder farmers use
Seed can be an important entry point for promoting productivity, nutrition and resilience among smallholder farmers. While investments have primarily focused on strengthening the formal sector, this article documents the degree to which the informal sector remains the core for seed acquisition, especially in Africa. Conclusions drawn from a uniquely comprehensive data set, 9660 observations across six countries and covering 40 crops, show that farmers access 90.2 % of their seed from informal systems with 50.9 % of that deriving from local markets. Further, 55 % of seed is paid for by cash, indicating that smallholders are already making important investments in this arena. Targeted interventions are proposed for rendering formal and informal seed sector more smallholder-responsive and for scaling up positive impacts
Infrared Variability of Evolved Protoplanetary Disks: Evidence for Scale Height Variations in the Inner Disk
We present the results of a multi-wavelength multi-epoch survey of five
evolved protoplanetary disks in the IC 348 cluster that show significant
infrared variability. Using 3-8micron and 24micron photometry along with
5-40micron spectroscopy from the Spitzer Space Telescope, as well as
ground-based 0.8-5micron spectroscopy, optical spectroscopy and near-infrared
photometry, covering timescales of days to years, we examine the variability in
the disk, stellar and accretion flux. We find substantial variations (10-60%)
at all infrared wavelengths on timescales of weeks to months for all of these
young stellar objects. This behavior is not unique when compared to other
cluster members and is consistent with changes in the structure of the inner
disk, most likely scale height fluctuations on a dynamical timescale. Previous
observations, along with our near-infrared photometry, indicate that the
stellar fluxes are relatively constant; stellar variability does not appear to
drive the large changes in the infrared fluxes. Based on our near-infrared
spectroscopy of the Pa-beta and Br-gamma lines we find that the accretion rates
are variable in most of the evolved disks but the overall rates are probably
too small to cause the infrared variability. We discuss other possible physical
causes for the variability, including the influence of a companion, magnetic
fields threading the disk, and X-ray flares.Comment: Accepted to ApJ. 33 pages, emulate apj forma
Elektronisk studentvurdering i praksisstudier. Fremmer det kvalitet og effektivitet?
Introduksjon: Praksisstudier utgjør fra 30–50 % av læringsaktivitetene i bachelorstudier innen helse- og sosialfagene. Praksisfeltet og utdanningsinstitusjonen har felles ansvar for å samarbeid om tilrettelegging av et læringsmiljø for studentene som gir mulighet for å oppnå læringsutbyttene. Både helsesektoren og universitets- og høgskolesektoren på nasjonalt nivå etterspør tekniske løsninger for å øke relevans, kvalitet og effektivitet i samhandlingen mellom partene i forbindelse med praksisstudier. Hensikt: Å styrke kvalitet og effektivitet i vurderingen av sykepleiestudenter i praksisstudier. Metode: Inspirert av aksjonsforskning, med reelt gjensidig samarbeid mellom helseinstitusjonene og utdanningsinstitusjonene. Utvalget var studenter, veiledere og kontaktlærere ved seks sykehusavdelinger. Elektronisk studentvurdering (ESV) ble utviklet og prøvd ut gjennom fire praksisperioder i spesialisthelsetjenesten. Resultater: ESV kan gi økt kontinuitet i studentveiledningen, skape større grad av felles forståelse for vurderingsgrunnlaget og tilrettelegge for hensiktsmessig tidsbruk i forbindelse med praksisstudier. Stort potensiale for kvalitetsutvikling av praksisstudier ligger i muligheten ESV gir for kontaktlærers regelmessige oppfølging av student og veileder. Konklusjon: For å utnytte ESVs potensiale fullt ut er lederforankring i både utdanningsinstitusjonen og praksisarenaen viktig for å sikre engasjerte og aktive studenter, veiledere og kontaktlærere. Mulighetene er store for å videreutvikle ESV for bruk i kommunehelsetjenesten og for andre profesjonsutdanninger med praksisstudier i sitt program. Nøkkelord: elektronisk verktøy, praksisstudier, vurdering, sykepleiestudentpublishedVersio
Fetal thoracic circumference and lung volume and their rlation to fetal size and pulmonary artery blood flow
Objective: Research on early origins of lung disease suggests the need for studying the relationships of thoracic and lung size with fetal size and pulmonary circulation. The primary aim of this study is therefore to explore the associations between fetal thoracic circumference, lung volume, and fetal size. We also aim to assess if lung volume and thoracic circumference are associated with fetal pulmonary artery blood flow velocity measures.
Methods: Cross-sectional assessment of singleton pregnancies from the general population (n = 447) at 30 gestational weeks (GW) was performed using ultrasound measurement of fetal thoracic circumference, lung volume, head and abdominal circumference, and femur length. We obtained Doppler blood flow velocity measures from the proximal branches of the fetal pulmonary artery. Associations between variables were studied using Pearson's correlation and multiple linear regression analyses.
Results: Both thoracic circumference and lung volume correlated with fetal size measures, ranging from r = 0.64 between thoracic circumference and abdominal circumference, to r = 0.28 between lung volume and femur length. Adjustment for gestational age, maternal nicotine use, pre-pregnancy body mass index, and fetal sex marginally influenced the associations with abdominal circumference. The correlations of thoracic circumference and lung volume with pulmonary artery blood flow velocity measures were weak (r ≤ 0.17).
Conclusion: We found moderate to low correlation between thoracic circumference, lung volume, and fetal size at 30 GW. The closest relationship was with the abdominal circumference. We found low correlations of thoracic circumference and lung volume with pulmonary artery blood flow velocity measures.publishedVersio
Bullying behaviour in schools, socioeconomic position and psychiatric morbidity: a cross-sectional study in late adolescents in Greece
<p>Abstract</p> <p>Background</p> <p>Bullying is quite prevalent in the school setting and has been associated with the socioeconomic position and psychiatric morbidity of the pupils. The aim of the study was to investigate the association between bullying and socioeconomic status in a sample of Greek adolescents and to examine whether this is confounded by the presence of psychiatric morbidity, including sub-threshold forms of illness.</p> <p>Methods</p> <p>5,614 adolescents aged 16-18 years old and attending 25 senior high schools were screened and a stratified random sample of 2,427 were selected for a detailed interview. Psychiatric morbidity was assessed with a fully structured psychiatric interview, the revised Clinical Interview Schedule (CIS-R), while bullying was assessed with the revised Olweus bully/victim questionnaire. The following socio-economic variables were assessed: parental educational level and employment status, financial difficulties of the family and adolescents' school performance. The associations were investigated using multinomial logit models.</p> <p>Results</p> <p>26.4% of the pupils were involved in bullying-related behaviours at least once monthly either as victims, perpetrators or both, while more frequent involvement (at least once weekly) was reported by 4.1%. Psychiatric morbidity was associated with all types of bullying-related behaviours. No socioeconomic associations were reported for victimization. A lower school performance and unemployment of the father were significantly more likely among perpetrators, while economic inactivity of the mother was more likely in pupils who were both victims and perpetrators. These results were largely confirmed when we focused on high frequency behaviours only. In addition, being overweight increased the risk of frequent victimization.</p> <p>Conclusions</p> <p>The prevalence of bullying among Greek pupils is substantial. Perpetration was associated with some dimensions of adolescents' socioeconomic status, while victimization showed no socioeconomic associations. Our findings may add to the understanding of possible risk factors for bullying behaviours in adolescence.</p
Rigorous monitoring is necessary to guide food system transformation in the countdown to the 2030 global goals
Food systems that support healthy diets in sustainable, resilient, just, and equitable ways can engender progress in eradicating poverty and malnutrition; protecting human rights; and restoring natural resources. Food system activities have contributed to great gains for humanity but have also led to significant challenges, including hunger, poor diet quality, inequity, and threats to nature. While it is recognized that food systems are central to multiple global commitments and goals, including the Sustainable Development Goals, current trajectories are not aligned to meet these objectives. As mounting crises further stress food systems, the consequences of inaction are clear. The goal of food system transformation is to generate a future where all people have access to healthy diets, which are produced in sustainable and resilient ways that restore nature and deliver just, equitable livelihoods.
A rigorous, science-based monitoring framework can support evidence-based policymaking and the work of those who hold key actors accountable in this transformation process. Monitoring can illustrate current performance, facilitate comparisons across geographies and over time, and track progress. We propose a framework centered around five thematic areas related to (1) diets, nutrition, and health; (2) environment and climate; and (3) livelihoods, poverty, and equity; (4) governance; and (5) resilience and sustainability. We hope to call attention to the need to monitor food systems globally to inform decisions and support accountability for better governance of food systems as part of the transformation process. Transformation is possible in the next decade, but rigorous evidence is needed in the countdown to the 2030 SDG global goals
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The state of food systems worldwide in the countdown to 2030
This Analysis presents a recently developed food system indicator framework and holistic monitoring architecture to track food system transformation towards global development, health and sustainability goals. Five themes are considered: (1) diets, nutrition and health; (2) environment, natural resources and production; (3) livelihoods, poverty and equity; (4) governance; and (5) resilience. Each theme is divided into three to five indicator domains, and indicators were selected to reflect each domain through a consultative process. In total, 50 indicators were selected, with at least one indicator available for every domain. Harmonized data of these 50 indicators provide a baseline assessment of the world’s food systems. We show that every country can claim positive outcomes in some parts of food systems, but none are among the highest ranked across all domains. Furthermore, some indicators are independent of national income, and each highlights a specific aspiration for healthy, sustainable and just food systems. The Food Systems Countdown Initiative will track food systems annually to
U. Rashid Sumaila, Maximo Torero Cullen, Francesco N. Tubiello, Jose-Luis Vivero-Pol, Patrick Webb & Keith Wieb
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