Modeling on-grate MSW incineration with experimental validation in a batch incinerator

This Article presents a 2-D steady-state model developed for simulating on-grate municipal solid waste incineration, termed GARBED-ss. Gas-solid reactions, gas flow through the porous waste particle bed, conductive, convective, and radiative heat transfer, drying and pyrolysis of the feed, the emission of volatile species, combustion of the pyrolysis gases, the formation and oxidation of char and its gasification by water vapor and carbon dioxide, and the consequent reduction of the bed volume are described in the bed model. The kinetics of the pyrolysis of cellulosic and noncellulosic materials were experimentally derived from experimental measurements. The simulation results provide a deep insight into the various phenomena involved in incineration, for example, the complete consumption of oxygen in a large zone of the bed and a consequent char-gasification zone. The model was successfully validated against experimental measurements in a laboratory batch reactor, using an adapted sister version in a transient regime. © 2010 American Chemical Society

Absorption Systems In Radio-Selected QSO Surveys

Radio-selected samples of quasars with complete optical identifications offer an ideal dataset with which to investigate dust bias associated with intervening absorption systems. Here, we review our work on the Complete Optical and Radio Absorption Line System (CORALS) survey whose aim is to quantify this bias and assess the impact of dust on absorber statistics. First, we review previously published results on the number density and gas content of high column density absorbers over the redshift range 0.6 < z < 3.5. We then present the latest results from CORALS which focus on measuring the metal content of our unbiased absorber sample and an investigation of their optical--IR colours. Overall we find that although dust is unarguably present in absorption galaxies, the level appears to be low enough that the statistics of previous magnitude limited samples have not been severely affected and that the subsequent reddening of background QSOs is small.Comment: Proceedings of IAUC199, Probing Galaxies through Quasar Absorption Lines, P. R. Williams, C. Shu, and B. Menard, ed

Selective effect of thiazides on the human osteoblast-like cell line MG-63

Selective effect of thiazides on the human osteoblast-like cell line MG-63. Thiazide diuretics have been shown to decrease bone-loss rate and to improve bone mineral density in patients using this medication. However, the exact role of thiazides on bone cells is still debated. In the present work, we studied whether thiazides could affect the normal features of osteoblasts using the human model cell line MG-63. Hydrochlorothiazide (HCTZ) did not affect cell growth nor DNA synthesis in these cells, yet slightly increased alkaline phosphatase activity in these cells at pharmacologically relevant concentrations. Under similar conditions, HCTZ dose-dependently inhibited 1,25(OH)2D3-induced osteocalcin secretion by these cells (maximal effect, -40 to 50%, P < 0.005). However, HCTZ did not inhibit the basal production of osteocalcin in MG-63 cells (without 1,25(OH)2D3 induction), which was very low to undectable. Two different thiazide derivatives, chlorothiazide and cyclothiazide, and two structurally related sulfonamides with selective inhibition of carbonic anhydrase (Acetazolamide) or hyperglycemic effects (Diazoxide) were also tested. Chlorothiazide (1000 µm) inhibited osteocalcin secretion (-42 ± 12.7%) at doses 10-fold higher than HCTZ (100 µm) while cyclothiazide was effective at doses of 1 µm(-27 ± 3.6%), and hence 100-fold lower than HCTZ, compatible with the relative natriuretic effect in vivo of these compounds. Acetazolamide (10 µm) poorly affected osteocalcin secretion at doses 100-fold higher than those needed in vivo to inhibit carbonic anhydrase. Likewise, Diazoxide (100 µm) poorly affected osteocalcin secretion at doses known to promote its biological effect. Higher doses of acetazolamide and diazoxide induced cell death. Neither Acetazolamide nor Diazoxide affected alkaline phosphatase, whereas chlorothiazide had a weak positive effect on this enzymatic activity. The production of macrophage colony-stimulating factor (M-CSF) was stimulated in the presence of 1,25(OH)2D3 (50nm), TNF-α (2 ng/ml) both in MG-63 cells. HCTZ (25 µm, 24hr of preincubation) did not modify basal M-CSF production and did not reduce the response to 1,25(OH)2D3 alone. In contrast, HCTZ inhibited the response to TNF-α alone (P < 0,05), and also reduced the response to a combination of 1,25(OH)2D3 and TNF-α (P < 0.01). In conclusion, these results indicate that thiazide diuretics show a selective inhibion of osteocalcin secretion and M-CSF production by MG-63 cells unlike structurally related drugs. Therefore, these features may explain, in part, the positive effect of thiazides on bone mineral density

Galaxy Morphology - Halo Gas Connections

We studied a sample of 38 intermediate redshift MgII absorption-selected galaxies using (1) Keck/HIRES and VLT/UVES quasar spectra to measure the halo gas kinematics from MgII absorption profiles and (2) HST/WFPC-2 images to study the absorbing galaxy morphologies. We have searched for correlations between quantified gas absorption properties, and host galaxy impact parameters, inclinations, position angles, and quantified morphological parameters. We report a 3.2-sigma correlation between asymmetric perturbations in the host galaxy morphology and the MgII absorption equivalent width. We suggest that this correlation may indicate a connection between past merging and/or interaction events in MgII absorption-selected galaxies and the velocity dispersion and quantity of gas surrounding these galaxies.Comment: 6 pages; 3 figures; contributed talk for IAU 199: Probing Galaxies through Quasar Absorption Line

Molecular hydrogen in the disk of the Herbig Ae star HD97048

We present high-resolution spectroscopic mid-infrared observations of the circumstellar disk around the Herbig Ae star HD97048 obtained with the VLT Imager and Spectrometer for the mid-InfraRed (VISIR). We conducted observations of mid-infrared pure rotational lines of molecular hydrogen (H2) as a tracer of warm gas in the disk surface layers. In a previous paper, we reported the detection of the S(1) pure rotational line of H2 at 17.035 microns and argued it is arising from the inner regions of the disk around the star. We used VISIR on the VLT for a more comprehensive study based on complementary observations of the other mid-infrared molecular transitions, namely S(2) and S(4) at 12.278 microns and 8.025 microns respectively, to investigate the physical properties of the molecular gas in the circumstellar disk around HD97048. We do not detect neither the S(2) line nor the S(4) H2 line from the disk of HD97048, but we derive upper limits on the integrated line fluxes which allows us to estimate an upper limit on the gas excitation temperature, T_ex < 570 K. This limit on the temperature is consistent with the assumptions previously used in the analysis of the S(1) line, and allows us to set stronger contraints on the mass of warm gas in the inner regions of the disk. Indeed, we estimate the mass of warm gas to be lower than 0.1 M_Jup. We also discuss the probable physical mechanisms which could be responsible of the excitation of H2 in the disk of HD97048.Comment: accepted for publication in Ap

Using AUC to study perceptual difference model suitability for the detection task on MR image

International audienceSince the ultimate goal of medical images is to help radiologists to gain a high diagnostic accuracy, evaluating the medical image quality from the radiologists' perspective is a useful alternative compared to optimal observer approach. While several existing perceptual difference models are adopted toward this end, few works were conducted to evaluate the suitability of the models w.r.t. the diagnostic task performance. This study is trying to address this problem

Diagnostic quality assessment of medical images: Challenges and trends

With medical imaging technologies growth, the question of their assessment on the impact and benefit on patient care is rising. Development and design of those medical imaging technologies should take into account the concept of image quality as it might impact the ability of practicians while they are using image information. Towards that goal, one should consider several human factors involved in image analysis and interpretation, e.g. image perception issues, decision process, image analysis pipeline (detection, localization, characterization...). While many efforts have been dedicated to objectively assess the value of imaging system in terms of ideal decision process, new trends have recently emerged to deal with human observer perfomances. This task effort is huge considering the variability of imaging acquisition methods and the possible pathologies. This paper proposes a survey of some key issues and results associated to this effort. We first outline the wide range of medical images with their own specific features. Next, we review the main methodologies to evaluate diagnostic quality of medical images from subjective assessment including ROC analysis, and diagnostic criteria quality analysis, to objective assessment including metrics based on the HVS, and model observers. At last, we present another evaluation method: eye-tracking studies to gain basic understanding of the visual search and decision-making process

Using eye-tracking to study diagnostic process during MRI scanning

International audienc