Kinetics of the reaction of nitric oxide with hydrogen

Mixtures of NO and H2 diluted in argon or krypton were heated by incident shock waves, and the infrared emission from the fundamental vibration-rotation band of NO at 5.3 microns was used to monitor the time-varying NO concentration. The reaction kinetics were studied in the temperature range 2400-4500 K using a shock-tube technique. The decomposition of nitric oxide behind the shock was found to be modeled well by a fifteen-reaction system. A principle result of the study was the determination of the rate constant for the reaction H + NO yields N + OH, which may be the rate-limiting step for NO removal in some combustion systems. Experimental values of k sub 1 were obtained for each test through comparisons of measured and numerically predicted NO profiles

Decomposition of NO studied by infrared emission and CO laser absorption

A diagnostic technique for monitoring the concentration of NO using absorption of CO laser radiation was developed and applied in a study of the decomposition kinetics of NO. Simultaneous measurements of infrared emission by NO at 5.3 microns were also made to validate the laser absorption technique. The data were obtained behind incident shocks in NO-N2O-Ar (or Kr) mixtures, with temperatures in the range 2400-4100 K. Rate constants for dominant reactions were inferred from comparisons with computer simulations of the reactive flow

Teacher Knowledge and Selection of Evidence-Based Practices: A survey study

Federal legislation and state and local policies mandate the use of evidence-based practices (EBPs) and aim to improve the quality of education for all students. Federal mandates (No Child Left Behind (NCLB) Act of 2001) coupled with teacher training requirements and the need for identifying effective practices for use with students with and without disabilities, highlight the need for teachers to not only implement EBPs but to identify such practices for implementation. The passage of NCLB marked the first time in education that the use of scientific research to inform instructional decisions was mandated

Seasonal variation of heavy metals (Cd, Pb and Hg) in sediments and in mullet, Mugil cephalus (Mugilidae), from the Ghar El Melh Lagoon (Tunisia)

1 - This study investigates the toxic contaminants cadmium (Cd), lead (Pb) and mercury (Hg) in surface sediments and in the fish species Mugil cephalus of the lagoon of Ghar El Melh (GEM), Tunisia. 2 - Sampling was conducted seasonally during 2003 and 2004. The results of this study indicated that levels of Cd and Pb varied in sediment from 0.4 to 0.9µgg-1dw and 25 to 70µgg-1dw, respectively. Mercury concentrations in sediment were generally below 1µgg-1dw. The highest level was observed in the north-east of lagoon. In fish muscle, concentrations of Cd, Pb and Hg varied between 0.013 to 0.025µgg-1dw, 0.048 to 0.422µgg-1dw and 0.222 to 0.409µgg-1dw, respectively. 3 - Results of heavy metal analyses in sediment and fish indicated that there were relatively metal contamination problems in GEM lagoon near the harbour due to the anthropogenic activities, notably from the Medjerda River and wastewater from the coastal towns around the lagoon

A continuous emissions monitor for metals: Field demonstration of a prototype probe

Sandia National Laboratories conducted field tests of a prototype continuous emissions monitor for metals at Clemson University, August 5-11, 1994, in cooperation with the joule-melter vitrification project at Clemson and Savannah River. The monitor is based on Laser Spark Spectroscopy, an established laboratory diagnostic technique that has been adapted for monitoring metal emissions from thermal waste treatment facilities. In the field tests described in this report, emissions were measured from a joule melter that was processing a surrogate waste-water treatment sludge from Oak Ridge. Data from this test provides the first insight into how emissions change (in real time) as operating parameters such as waste feed rate are changed. We detected all metals that were present above the estimated minimum detectability limits (in the parts-per-billion range for Clean Air Act metals), in addition to glass-making species such as calcium, boron, and silicon. This report summarizes the Clemson field tests, including design of the prototype probe, preparations leading up to the tests, the tests themselves, and analysis of results

The Spatial Distribution of Atomic Carbon Emission in the Giant Molecular Cloud NGC 604-2

We have mapped a giant molecular cloud in the giant HII region NGC 604 in M33 in the 492 GHz ^3P_1 -- ^3P_0 transition of neutral atomic carbon using the James Clerk Maxwell Telescope. We find the distribution of the [CI] emission to be asymmetric with respect to the CO J=1--0 emission, with the peak of the [CI] emission offset towards the direction of the center of the HII region. In addition, the line ratio I_{[CI]}/I_{CO} is highest (~ 0.2) facing the HII region and lowest (< 0.1) away from it. These asymmetries indicate an edge-on morphology where the [CI] emission is strongest on the side of the cloud facing the center of the HII region, and not detected at all on the opposite side This suggests that the sources of the incident flux creating C from the dissociation of CO are the massive stars of the HII region. The lowest line ratios are similar to what is observed in Galactic molecular clouds, while the highest are similar to starburst galaxies and other regions of intense star formation. The column density ratio, N(C)/N(H_2) is a few times 10^{-6}, in general agreement with models of photodissociation regions.Comment: Accepted for publication in ApJ. 8 pages, 5 figures, 3 table

Near-Infrared Spectroscopy of Molecular Hydrogen Emission in Four Reflection Nebulae: NGC 1333, NGC 2023, NGC 2068, and NGC 7023

We present near-infrared spectroscopy of fluorescent molecular hydrogen (H_2) emission from NGC 1333, NGC 2023, NGC 2068, and NGC 7023 and derive the physical properties of the molecular material in these reflection nebulae. Our observations of NGC 2023 and NGC 7023 and the physical parameters we derive for these nebulae are in good agreement with previous studies. Both NGC 1333 and NGC 2068 have no previously-published analysis of near-infrared spectra. Our study reveals that the rotational-vibrational states of molecular hydrogen in NGC 1333 are populated quite differently from NGC 2023 and NGC 7023. We determine that the relatively weak UV field illuminating NGC 1333 is the primary cause of the difference. Further, we find that the density of the emitting material in NGC 1333 is of much lower density, with n ~ 10^2 - 10^4 cm^-3. NGC 2068 has molecular hydrogen line ratios more similar to those of NGC 7023 and NGC 2023. Our model fits to this nebula show that the bright, H_2-emitting material may have a density as high as n ~ 10^5 cm^-3, similar to what we find for NGC 2023 and NGC 7023. Our spectra of NGC 2023 and NGC 7023 show significant changes in both the near-infrared continuum and H_2 intensity along the slit and offsets between the peaks of the H_2 and continuum emission. We find that these brightness changes may correspond to real changes in the density and temperatures of the emitting region, although uncertainties in the total column of emitting material along a given line of sight complicates the interpretation. The spatial difference in the peak of the H_2 and near-infrared continuum peaks in NGC 2023 and NGC 7023 shows that the near-infrared continuum is due to a material which can survive closer to the star than H_2 can.Comment: Submitted for publication in ApJ. 34 pages including 12 embedded postscript figures. Also available at http://www.astronomy.ohio-state.edu/~martini/pub

Using keystroke logging to understand writers’ processes on a reading-into-writing test

Background Integrated reading-into-writing tasks are increasingly used in large-scale language proficiency tests. Such tasks are said to possess higher authenticity as they reflect real-life writing conditions better than independent, writing-only tasks. However, to effectively define the reading-into-writing construct, more empirical evidence regarding how writers compose from sources both in real-life and under test conditions is urgently needed. Most previous process studies used think aloud or questionnaire to collect evidence. These methods rely on participants’ perceptions of their processes, as well as their ability to report them. Findings This paper reports on a small-scale experimental study to explore writers’ processes on a reading-into-writing test by employing keystroke logging. Two L2 postgraduates completed an argumentative essay on computer. Their text production processes were captured by a keystroke logging programme. Students were also interviewed to provide additional information. Keystroke logging like most computing tools provides a range of measures. The study examined the students’ reading-into-writing processes by analysing a selection of the keystroke logging measures in conjunction with students’ final texts and interview protocols. Conclusions The results suggest that the nature of the writers’ reading-into-writing processes might have a major influence on the writer’s final performance. Recommendations for future process studies are provided

North Atlantic Intermediate to Deep Water circulation and chemical stratification during the past 1 Myr

Benthic foraminiferal carbon isotope records from a suite of drill sites in the North Atlantic are used to trace variations in the relative strengths of Lower North Atlantic Deep Water (LNADW), Upper North Atlantic Deep Water (UNADW), and Southern Ocean Water (SOW) over the past 1 Myr. During glacial intervals, significant increases in intermediate-to-deep δ13C gradients (commonly reaching >1.2‰) are consistent with changes in deep water circulation and associated chemical stratification. Bathymetric δ13C gradients covary with benthic foraminiferal δ18O and covary inversely with Vostok CO2, in agreement with chemical stratification as a driver of atmospheric CO2 changes. Three deep circulation indices based on δ13C show a phasing similar to North Atlantic sea surface temperatures, consistent with a Northern Hemisphere control of NADW/SOW variations. However, lags in the precession band indicate that factors other than deep water circulation control ice volume variations at least in this band