The FERRUM project: Transition probabilities for forbidden lines in [FeII] and experimental metastable lifetimes

Accurate transition probabilities for forbidden lines are important diagnostic parameters for low-density astrophysical plasmas. In this paper we present experimental atomic data for forbidden [FeII] transitions that are observed as strong features in astrophysical spectra. Aims: To measure lifetimes for the 3d^6(^3G)4s a ^4G_{11/2} and 3d^6(^3D)4s b ^4D_{1/2} metastable levels in FeII and experimental transition probabilities for the forbidden transitions 3d^7 a ^4F_{7/2,9/2}- 3d^6(^3G)4s a ^4G_{11/2}. Methods: The lifetimes were measured at the ion storage ring facility CRYRING using a laser probing technique. Astrophysical branching fractions were obtained from spectra of Eta Carinae, obtained with the Space Telescope Imaging Spectrograph onboard the Hubble Space Telescope. The lifetimes and branching fractions were combined to yield absolute transition probabilities. Results: The lifetimes of the a ^4G_{11/2} and the b ^4D_{1/2} levels have been measured and have the following values, 0.75(10) s and 0.54(3) s respectively. Furthermore, we have determined the transition probabilities for two forbidden transitions of a ^4F_{7/2,9/2}- a ^4G_{11/2} at 4243.97 and 4346.85 A. Both the lifetimes and the transition probabilities are compared to calculated values in the literature.Comment: 5 pages, accepted for publication in A&

CHIANTI - An Atomic Database for Emission Lines. XII. Version 7 of the Database

The CHIANTI spectral code consists of an atomic database and a suite of computer programs to calculate the optically thin spectrum of astrophysical objects and carry out spectroscopic plasma diagnostics. The database includes atomic energy levels, wavelengths, radiative transition probabilities, collision excitation rate coefficients, and ionization and recombination rate coefficients, as well as data to calculate free-free, free-bound, and two-photon continuum emission. Version 7 has been released, which includes several new ions, significant updates to existing ions, as well as Chianti-Py, the implementation of CHIANTI software in the Python programming language. All data and programs are freely available at http://www.chiantidatabase.org, while the Python interface to CHIANTI can be found at http://chiantipy.sourceforge.net.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98606/1/0004-637X_744_2_99.pd

Log <i>gf</i> values for astrophysically important transitions Fe II

Aims. In a recent measurement, Meléndez & Barbuy (2009, A&A, 497, 611) report accurate log  gf values for 142 important astrophysical lines with wavelengths in the range 4000 Å to 8000 Å. Their results include both solar and laboratory measurements. In this paper, we describe a theoretical study of these lines. Methods. The CIV3 structure codes, combined with our “fine-tuning” extrapolation process, are used to undertake a large-scale CI calculation involving the lowest 262 fine-structure levels belonging to the 3d64s, 3d7, 3d54s2, 3d64p, and 3d54s4p configurations. Results. We find that many of the 142 transitions are very weak intercombination lines. Other transitions are weak because the dominant configurations in the two levels differ by two orbitals. Conclusions. The comparison between our log gf values and the experimental values generally shows good agreement for most of these transitions, with our theoretical values agreeing slightly more closely with the solar than with the laboratory measurements. A detailed analysis of the small number of transitions for which the agreement between theory and experiment is not as good shows that such disagreements largely arise from severe cancellation due to CI mixing

Group Size and Peer Learning: Peer Discussions in Different Group Size Influence Learning in a Biology Exercise Performed on a Tablet With Stylus

International audienceDetermining the optimal discussion group size to improve performance and learning has created an intense debate in psychology and provided mixed findings in laboratory and field settings. In a quasi-experimental study in the education field, we examined the effect of discussion group size on individual learning in a biology exercise performed on a tablet with stylus. The sample involved 102 secondary school students divided into four classes, each corresponding to one of the four experimental conditions (alone without peer discussion vs discussion in dyads vs triads vs four-member groups). They were asked to draw individually a functional schema of the human respiratory system, once before and once after discussing with peers (or reflecting alone). Both drawings were evaluated by four independent coders, and the learning gain for each student was computed from these evaluations. Results revealed that learning gain was greater for students discussing in four-member groups than for those in the other conditions. Additional analyses suggested that this effect was moderated by the students' gender, with the learning gain being greater after discussion in four-member groups among females only. These findings suggest that group size of four individuals might be the optimal configuration to improve peer learning

Impact de l’âge au sevrage sur la prévalence des diarrhées

International audienceThe practice of weaning at 21 days of age has developed considerably in France. The objective of this trial was to study the impact of the age of piglets at weaning (at 21 or 28 days of age) on pig health after weaning under normal or degraded conditions of live. The study was performed in experimental facilities on two batches of 252 piglets from weaning until seven weeks after weaning. A feeding practice with a secure feed during the first 7 days of post-weaning was implemented for pigs weaned at 21 days. Mortality rate was recorded, and diarrhea was assessed by analyzing fecal scores and measuring the dry matter content of the feces. Blood was collected from 160 piglets (to analyze the complete blood count, haptoglobin, antioxidant defense and the production of reactive oxygen species. During the post-weaning period, 47% of piglets were observed to have diarrhea on at least one day, and this percentage was not significantly influenced by age at weaning. The piglets weaned at 21 days of age had a 7-day lag in the onset of diarrhea compared to those weaned at 28 days of age. Animals weaned at 21 days under normal conditions have a higher mortality rate than those weaned at 28 days but not under degraded conditions. These results should be confirmed by other studies

Energy levels, radiative rates, and excitation rates for transitions in OIV

Aims.In this paper we report calculations for energy levels, radiative rates and excitation rates for transitions in Ni x

Social norms from a goal-system point of view: Contributions of activity analysis

International audienceIn this article, we used a social injunctive norm to incentivize the elaboration of energy-efficientprojects within a building renovation simulation application. We manipulated the norm saliency(presence on the interface) and compared its effect to that of an arbitrary set goal and a no-goalcondition (control). Results show that both an injunctive norm and an explicit goal, when salient,led to more energy-efficient designs. Furthermore, participants exposed to the salient injunctivenorm identified important parameters more quickly, were more efficient, and were moreconsistently focused on energy (vs. furnishing). Implications for theory and methodology forfurther experiments are discussed

Using Regulatory Focus Theory for a Mobile Device Renovation Application: Nudging Users Towards Building Green Houses

International audienceWe propose a preliminary study aiming to apply RegulatoryFocus Theory to building renovations. We developed a mobile applicationto test if a priming technique could influence users and the choicesthey make when it comes to select equipment such as a heater or thermalinsulation. First results show that choices might be affected by thepriming task. The question remains though as to how to ecologically andnon-intrusively prime users of such applications