Atomic Processes in Planetary Nebulae and H II Regions

Spectroscopic studies of Planetary Nebulae (PNe) and H {\sc ii} regions have driven much development in atomic physics. In the last few years the combination of a generation of powerful observatories, the development of ever more sophisticated spectral modeling codes, and large efforts on mass production of high quality atomic data have led to important progress in our understanding of the atomic spectra of such astronomical objects. In this paper I review such progress, including evaluations of atomic data by comparisons with nebular spectra, detection of spectral lines from most iron-peak elements and n-capture elements, observations of hyperfine emission lines and analysis of isotopic abundances, fluorescent processes, and new techniques for diagnosing physical conditions based on recombination spectra. The review is directed toward atomic physicists and spectroscopists trying to establish the current status of the atomic data and models and to know the main standing issues.Comment: 9 pages, 1 figur

Chemical Abundances from the Continuum

The calculation of solar absolute fluxes in the near-UV is revisited, discussing in some detail recent updates in theoretical calculations of bound-free opacity from metals. Modest changes in the abundances of elements such as Mg and the iron-peak elements have a significant impact on the atmospheric structure, and therefore self-consistent calculations are necessary. With small adjustments to the solar photospheric composition, we are able to reproduce fairly well the observed solar fluxes between 200 and 270 nm, and between 300 and 420 nm, but find too much absorption in the 270-290 nm window. A comparison between our reference 1D model and a 3D time-dependent hydrodynamical simulation indicates that the continuum flux is only weakly sensitive to 3D effects, with corrections reaching <10% in the near-UV, and <2% in the optical.Comment: 10 pages, 5 figures, to appear in the proceedings of the conference A Stellar Journey, a symposium in celebration of Bengt Gustafsson's 65th birthday, June 23-27, 2008, Uppsal

Removal of anionic surfactant from aqueous solutions by adsorption onto biochars:characterisation, kinetics, and mechanism

Biochar, a waste biomass-derived adsorbent, holds promise for decentralised wastewater treatment. However, limited research exists on its efficacy in adsorbing anionic surfactants in wastewater. To address this, the adsorption of sodium dodecyl sulphate (SDS), a common anionic surfactant, was studied using various biochar types: rice husk biochar (RH-550 and RH-700), wheat straw biochar (WS-550 and WS-700) produced at 550°C and 700°C, wood-based biochar (OB), and activated carbon (AC) as a control. The study investigated the impact of pH (3–9), adsorbent loading (1–10 g/L), adsorbent size (&lt;0.5–2.5 mm), contact time (5–180 min), and initial concentration (50–200 mg/L) on SDS removal. Under optimised conditions (100 mg/L SDS, 4 g/L adsorbent, 1–2 mm particle size, pH 8.3, and 180 min contact time), maximum SDS removals were RH-550 (78%), RH-700 (82.4%), WS-550 (89.5%), WS-700 (90.4%), AC (97%), and OB (88.4%). Among the tested adsorbent materials, WS-550 exhibited the highest SDS adsorption capacity at 66.23 mg/g compared to AC (80.65 mg/g), followed by RH-550 (49.75 mg/g), OB (45.87 mg/g), RH-700 (43.67 mg/g), and WS-700 (42.74 mg/g). SDS adsorption followed a pseudo-second-order kinetic model, indicating chemisorption on the adsorbent surface. The Freundlich isotherm model exhibited a better fit for the experimental data on SDS adsorption using all tested adsorbents except for RH-550. This study showed that biochars produced from agricultural and forestry residues are effective adsorbents for SDS in aqueous solutions and can be a promising sustainable and low-cost material for the treatment of greywater containing anionic surfactants (e.g. handwashing, laundry, kitchen, and bathroom greywaters)

Determining the Locations of Dust Sources in FeLoBAL Quasars

We conduct a spectroscopic search of quasars observed by the Sloan Digital Sky Survey (SDSS) with broad absorption line (BAL) troughs due to Mg II and troughs due to Fe II that simultaneously exhibit strong Balmer narrow emission lines (NELs). We find that in a redshift range of 0.4 less than or equal to z less than or equal to 0.9 approximately 23 of the 70 Mg II BALs and 4 of a subset of 15 Fe II BALs exhibit strong Balmer emission. We also find significant fractions of Mg II BALs (approximately 23%) and those Mg II BALs with Fe II troughs (approximately 27%) have strong continuum reddening, E(B - V) greater than or equal to 0.1. From measurements of the Balmer decrement in three objects, we find similarly significant reddening of the NEL region in three of the four objects; the NELs in the fourth object are not measurable. We also include one object in this study not taken from the SDSS sample that shows Fe II absorption and strong narrow emission, but due to measurement uncertainty and low continuum reddening the comparison is consistent but inconclusive. We find a trend in both the Mg II and Fe II BAL samples between the NEL reddening and continuum reddening. Because the narrow line reddening is consistent with the continuum reddening in every object in the two SDSS samples, it suggests that the reddening sources in these objects likely exist at larger radial distances than the narrow line regions from the central nucleus.Comment: 40 manuscript pages, accepted in ApJ (July

Elliptic flow from color strings

It is shown that the elliptic flow can be successfully described in the color string picture with fusion and percolation provided anisotropy of particle emission from the fused string is taken into account. Two possible sources of this anisotropy are considered, propagation of the string in the transverse plane and quenching of produced particles in the strong color field of the string. Calculations show that the second source gives an overwhelming contribution to the flow at accessible energies.Comment: 23 pages, 11 figure

Particle production azimuthal asymmetries in a clustering of color sources model

The collective interactions of many partons in the first stage of the collisions is the usual accepted explanation of the sizable elliptical flow. The clustering of color sources provides a framework of partonic interactions. In this scheme, we show a reasonable agreement with RHIC data for pT<1.5 GeV/c in both the dependence of v2 transverse momentum and in the shape of the nuclear modified factor on the azimuthal angle for different centralities. We show the predictions at LHC energies for Pb-Pb. In the case of proton-proton collisions a sizable v2 is obtained at this energy.Comment: To appear in Journal of Physics

Loop Quantization of the Supersymmetric Two-Dimensional BF Model

In this paper we consider the quantization of the 2d BF model coupled to topological matter. Guided by the rigid supersymmetry this system can be viewed as a super-BF model, where the field content is expressed in terms of superfields. A canonical analysis is done and the constraints are then implemented at the quantum level in order to construct the Hilbert space of the theory under the perspective of Loop Quantum Gravity methods.Comment: 17 pages, Late

Cost of tuberculosis treatment in low- and middle-income countries: systematic review and meta-regression.

BACKGROUND: Despite a scarcity of tuberculosis (TB) cost data, a substantial body of evidence has been accumulating for drug-susceptible TB (DS-TB) treatment. In this study, we review unit costs for DS-TB treatment from a provider´s perspective. We also examine factors driving cost variations and extrapolate unit costs across low- and middle-income countries (LMICs).METHODS: We searched published and grey literature for any empirically collected TB cost estimates. We selected a subgroup of estimates looking at DS-TB treatment. We extracted information on activities and inputs included. We standardised costs into an average per person-month, fitted a multi-level regression model and cross-validated country-level predictions. We then extrapolated estimates for facility-based, directly observed DS-TB treatment across countries.RESULTS: We included 95 cost estimates from 28 studies across 17 countries. Costs predictions were sensitive to characteristics such as delivery mode, whether hospitalisation was included, and inputs accounted for, as well as gross domestic product per capita. Extrapolation results are presented with uncertainty intervals (UIs) for LMICs. Predicted median costs per 6 months of treatment were US$315.30 (95$222.60-US$417.20) for low-income, US$527.10 (95% CI US$395.70-US$743.70) for lower middle-income and US$896.40 (95$654.00-US$1214.40) for upper middle-income countries.CONCLUSIONS: Our study provides country-level DS-TB treatment cost estimates suitable for priority setting. These estimates, while not standing as a substitute for local high-quality primary data, can inform global, regional and national exercises