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&

The FERRUM project: laboratory-measured transition probabilities for Cr II

Aims: We measure transition probabilities for Cr II transitions from the z ^4H_J, z ^2D_J, y ^4F_J, and y ^4G_J levels in the energy range 63000 to 68000 cm^{-1}. Methods: Radiative lifetimes were measured using time-resolved laser-induced fluorescence from a laser-produced plasma. In addition, branching fractions were determined from intensity-calibrated spectra recorded with a UV Fourier transform spectrometer. The branching fractions and radiative lifetimes were combined to yield accurate transition probabilities and oscillator strengths. Results: We present laboratory measured transition probabilities for 145 Cr II lines and radiative lifetimes for 14 Cr II levels. The laboratory-measured transition probabilities are compared to the values from semi-empirical calculations and laboratory measurements in the literature.Comment: 13 pages. Accepted for publication in A&

Ammonia Measurements and Emissions from a California Dairy Using Point and Remote Sensors

Ammonia (NH3) is an important trace gas species in the atmosphere that can have negative impacts on human, animal, and ecosystem health. Agriculture has been identified as the largest source of NH3, specifically livestock operations. NH3 emissions from a commercial dairy in California were investigated during June 2008. Cattle were held in open-lot pens, except for young calves in hutches with shelters. Solid manure was stored in the open-lot pens. Liquid manure from feed lanes was passed through a solids settling basin and stored in a holding pond. Passive sensors and openpath Fourier transform infrared spectrometers (OP-FTIR) were deployed around the facility to measure NH3 concentrations. Emissions from pens and the liquid manure system (LMS) were estimated using inverse modeling. Mean emission factors (EFs) for the entire facility were 140.5 ±42.5 g d-1 animal-1 from the passive sampler data and 199.2 ±22.0 g d-1 animal-1 from the OP-FTIR data, resulting in the facility’s summer emissions calculated at 265.2 ±80.2 kg d-1 and 375.4 ±27.1 kg d-1, respectively. These EFs are within the range of values reported in the literature. Both concentrations and emissions exhibited a strong diurnal cycle, peaking in the late afternoon. Total facility emissions exhibited significant positive correlations with temperature and wind speed. The findings of this study show that NH3 emissions from a commercial dairy can vary by a factor of 10 or more throughout the day, and EFs can vary by two orders of magnitude when compared to other U.S. dairies, based on literature values

Electrophilic PPARγ Ligands Attenuate IL-1β and Silica-Induced Inflammatory Mediator Production in Human Lung Fibroblasts via a PPARγ-Independent Mechanism

Acute and chronic lung inflammation is associated with numerous important disease pathologies including asthma, chronic obstructive pulmonary disease and silicosis. Lung fibroblasts are a novel and important target of anti-inflammatory therapy, as they orchestrate, respond to, and amplify inflammatory cascades and are the key cell in the pathogenesis of lung fibrosis. Peroxisome proliferator-activated receptor gamma (PPARγ) ligands are small molecules that induce anti-inflammatory responses in a variety of tissues. Here, we report for the first time that PPARγ ligands have potent anti-inflammatory effects on human lung fibroblasts. 2-cyano-3, 12-dioxoolean-1, 9-dien-28-oic acid (CDDO) and 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) inhibit production of the inflammatory mediators interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), COX-2, and prostaglandin (PG)E2 in primary human lung fibroblasts stimulated with either IL-1β or silica. The anti-inflammatory properties of these molecules are not blocked by the PPARγ antagonist GW9662 and thus are largely PPARγ independent. However, they are dependent on the presence of an electrophilic carbon. CDDO and 15d-PGJ2, but not rosiglitazone, inhibited NF-κB activity. These results demonstrate that CDDO and 15d-PGJ2 are potent attenuators of proinflammatory responses in lung fibroblasts and suggest that these molecules should be explored as the basis for novel, targeted anti-inflammatory therapies in the lung and other organs

Astronomy & Astrophysics The FERRUM project: laboratory-measured transition probabilities for Cr II

ABSTRACT Aims. We measure transition probabilities for Cr ii transitions from the z 4 H J , z 2 D J , y 4 F J , and y 4 G J levels in the energy range 63 000 to 68 000 cm −1 . Methods. Radiative lifetimes were measured using time-resolved laser-induced fluorescence from a laser-produced plasma. In addition, branching fractions were determined from intensity-calibrated spectra recorded with a UV Fourier transform spectrometer. The branching fractions and radiative lifetimes were combined to yield accurate transition probabilities and oscillator strengths. Results. We present laboratory measured transition probabilities for 145 Cr ii lines and radiative lifetimes for 14 Cr ii levels. The laboratory-measured transition probabilities are compared to the values from semi-empirical calculations and laboratory measurements in the literature

The FERRUM Project: experimental and theoretical transition rates of forbidden [Sc II] lines and radiative lifetimes of metastable Sc II levels

Context. In many plasmas, long-lived metastable atomic levels are depopulated by collisions (quenched) before they decay radiatively. In low-density regions, however, the low collision rate may allow depopulation by electric dipole (E1) forbidden radiative transitions, so-called forbidden lines (mainly M1 and E2 transitions). If the atomic transition data are known, these lines are indicators of physical plasma conditions and used for abundance determination. Aims. Transition rates can be derived by combining relative intensities between the decay channels, so-called branching fractions (BFs), and the radiative lifetime of the common upper level. We use this approach for forbidden [Sc ii] lines, along with new calculations. Methods. Neither BFs for forbidden lines, nor lifetimes of metastable levels, are easily measured in a laboratory. Therefore, astrophysical BFs measured in Space Telescope Imaging Spectrograph (STIS) spectra of the strontium filament of Eta Carinae are combined with lifetime measurements using a laser probing technique on a stored ion-beam (CRYRING facility,MSL, Stockholm). These quantities are used to derive the absolute transition rates (A-values). New theoretical transition rates and lifetimes are calulated using the CIV3 code. Results. We report experimental lifetimes of the Sc ii levels 3d2 a3P0,1,2 with lifetimes 1.28, 1.42, and 1.24 s, respectively, and transition rates for lines from these levels down to 3d4s a3D in the region 8270-8390 A. These are the most important forbidden [Sc ii] transitions. New calculations for lines and metastable lifetimes are also presented, and are in good agreement with the experimental data.Comment: 5 pages. Accepted for A&

Wavelengths, energy levels and hyperfine structure constants in Ho II

We recorded spectra of Ho II emitted by hollow-cathode lamps, using the ultraviolet Fourier transform spectrometer (FTS) at Lund Observatory and the 2-m FTS at the National Institute of Standards and Technology. The combined wavenumber coverage spans the interval from 8000 to 49 600 cm(-1) (12 500 to 2016 angstrom). We measured 303 lines in these spectra and used them to determine energies and hyperfine structure constants of 100 levels. Of these, 41 energy levels have not been reported previously and hyperfine structure constants have not been reported previously for 83 levels. Comparisons between the hyperfine structure constants and energy levels presented in this article and those previously determined from other studies are included and discrepancies are discussed. A theoretical study of the odd-parity levels leads to hyperfine structure parameters and to predictions for unknown excited levels of the ground-state configuration

Wavelengths, energy levels and hyperfine structure constants in Ho ii

International audienceWe recorded spectra of Ho ii emitted by hollow-cathode lamps, using the ultraviolet Fourier transform spectrometer (FTS) at Lund Observatory and the 2-m FTS at the National Institute of Standards and Technology. The combined wavenumber coverage spans the interval from 8000 to 49 600 cm-1 (12 500 to 2016 Å). We measured 303 lines in these spectra and used them to determine energies and hyperfine structure constants of 100 levels. Of these, 41 energy levels have not been reported previously and hyperfine structure constants have not been reported previously for 83 levels. Comparisons between the hyperfine structure constants and energy levels presented in this article and those previously determined from other studies are included and discrepancies are discussed. A theoretical study of the odd-parity levels leads to hyperfine structure parameters and to predictions for unknown excited levels of the ground-state configuration

Metastable levels in Sc II: lifetime measurements and calculations

The lifetime of the metastable level 3d(21)G(4) in a singly charged scandium has been experimentally investigated at the ion storage ring CRYRING. A laser probing technique has been used for the studies. We also report calculated lifetimes and transition rates for 10 metastable levels in Sc II, including the 3d(21)G(4) state, by calculations using configuration interaction wave functions. The lifetime of the (1)G(4) level is experimentally determined to be tau(exp) = 2.64 +/- 0.18 s and is in good agreement with the theoretical calculation tau(th) = 2.84 s