Interactive experimenters' planning procedures and mission control

The computerized mission control and planning system routinely generates a 24-hour schedule in one hour of operator time by including time dimensions into experimental planning procedures. Planning is validated interactively as it is being generated segment by segment in the frame of specific event times. The planner simply points a light pen at the time mark of interest on the time line for entering specific event times into the schedule

Misalignment estimation software system

A system of computer software, spacecraft, and ground system activity is described that enables spacecraft startrackers and inertial assemblies to be aligned and calibrated from the ground after the spacecraft has achieved orbit. The system generates in the uplink flow an exercise designed to render misalignments visible, and sends the exercise to the spacecraft where the spacecraft inserts the misalignment into the information in the form of attitude sensor error. The information is downlinked for processing into misalignment estimates to be used for correcting spacecraft model at data base

The impact of agriculture on climate change

The impact of agriculture on climate change is not fully understood, but it is clear that the human role is considerably more than the increase in GHG concentration. Agroecosystems are intensively managed, and as farming practices evolve the role of agriculture will change. Agricultural practices can influence climate through a modification of the surface energy budget as well as through GHG emissions

Assessing the Impact of a Change in Institutional Aid Policy: A Simulation Tool

This article describes the development and use of a simulation model designed to assist institutional policy makers in assessing a proposal to discount non-resident student tuition by offering a new institutional scholarship. The model proved to be a valuable tool for administrators in evaluating a wide range of policy alternatives, in the areas of enrollment, quality of the class, and net tuition revenue effects

GEMPAK5 user's guide, version 5.0

GEMPAK is a general meteorological software package used to analyze and display conventional meteorological data as well as satellite derived parameters. The User's Guide describes the GEMPAK5 programs and input parameters and details the algorithms used for the meteorological computations

Age-Related Changes in Listening Effort for Various Types of Masker Noises

It is well established that older listeners have more difficulty understanding speech in background noise than younger listeners (e.g. Dubno et. al., 1984). Some have attributed this increased difficulty to peripheral hearing loss, while others suggest that older listeners may perceive listening in noise as difficult and effortful because it requires them to exert more cognitive resources (Desjardins et. al., 2009). The purpose of the present study was to directly evaluate the relationship between cognitive function, listening effort and speech recognition for a group of younger and older normal hearing adults, and a group of older adults with hearing impairment, in various types of background noise. A dual-task paradigm was used to objectively evaluate listening effort. The primary task required participants to repeat sentences presented in three different background noise masker conditions (e.g. Two-Talker (TT), Six-Talker (SIX), Speech-Shaped Noise (SSN)). The secondary task was a digital visual pursuit rotor tracking test (DPRT), for which participants were instructed to use a computer mouse to track a moving target around an ellipse that was displayed on a computer screen. Each task was presented separately and concurrently at a fixed speech recognition performance level of 76% correct. In addition, participants\u27 subjectively rated how easy it was to listen to the sentences in each masker condition on a scale from 0 (e.g. very difficult) to 100 (e.g. very easy). Last, participants completed a battery of cognitive tests which measured working memory (Reading Span test), processing speed (DSST) and selective attention (Stroop test) ability. Results revealed that participants\u27 working memory and processing speed ability were significantly related to their speech recognition performance in noise in all three background noise masker conditions. Both groups of older participants expended significantly more listening effort than younger participants in the SSN and TT masker conditions. For each group of participants, there were no significant differences in listening effort measured across the masker conditions, with the exception of the younger participants who expended more effort listening in the SIX masker condition compared to the SSN condition. All participants\u27 listening effort expended on the TT and SSN masker conditions was significantly correlated with their working memory and processing speed performance. Participants\u27 subjective ratings of listening effort did not correlate with their objective measures of listening effort on any of the listening conditions. Findings from the present study indicate that older adults, independent of peripheral hearing loss, require more cognitive resources than younger adults to understand speech in background noise

The Effects of Interrupted Enrollment on Graduation from College: Racial, Income, and Ability Differences

We present a multiple spells-competing risks model of stopout, dropout, reenrollment, and graduation behavior. We find that students who experience an initial stopout are more likely to experience subsequent stopouts (occurrence dependence) and be less likely to graduate. We also find evidence of the impact of the length of an initial spell on the probability of subsequent events (lagged duration dependence). We simulate the impacts of race, family income, and high school performance on student behavior and show that there are often very large differences between unadjusted rates of student outcomes and adjusted rates. Differences in student performance often ascribed to race are shown to be the result of income, age at entry, and high school performance.

Évolution de la qualité de l'eau dans le réseau de distribution de la ville de Montréal

Dans la présente étude, nous montrons l'évolution de l'eau dans un réseau de distribution. Ce réseau a été construit dans les années 70 à l'aide de conduites d'acier ou de fonte ductile munies d'un revêtement intérieur de ciment. Il est alimenté par des eaux de très bonne qualité qui circulent d'abord dans une suite de conduites maîtresses (de 2 700 mm à 900 mm) jusqu'à un secteur de petites conduites maillées (200 et 300 mm). Des échantillons d'eau ont été prélevés à 14 reprises durant une année, le long de la conduite maîtresse (le temps de séjour y varie de 0 h à 13,6 h) et dans le secteur de petites conduites (de 13,6 h à 18,4 h). Nous avons mesuré la température, le pH, plusieurs sous-produits de désinfection dont les trihalométhanes et les aldéhydes, le carbone organique total et biodégradable ainsi que les concentrations de bactéries hétérotrophes aérobies et anaérobies facultatives (BHA) et les comptes directs totaux mesurés en épifluorescence. Le réseau a très peu d'effet sur l'évolution des sous-produits de désinfection. En effet, les résultats obtenus à partir des échantillons témoins (eaux traitées conservées dans un flacon propre à la même température que dans le réseau) sont semblables à ceux obtenus à partir des eaux prélevées dans le réseau de distribution.Les concentrations de bactéries ainsi que les concentrations de CODB sont assez stables dans le réseau. Il est intéressant de noter qu'il y a de 0,2 à 0,45 mg/l de CODB, ce qui est supérieur à la concentration minimale de 0,15 mg/l requise pour la croissance des bactéries. Par contre, le chlore résiduel libre est toujours supérieur à 0,20 mg/l. Une seule exception, le 11 juillet 1994, dans le secteur de petites conduites, le chlore résiduel a baissé jusqu'à 0,16 mg/l. Durant cette journée, nous avons observé une légère augmentation des comptes directs totaux mesurés en épifluorescence.Studies were performed to follow the changes in water quality along a distribution system. The distribution system under study is divided into two parts: main pipes starting from the plant (from 2 700 mm to 900 mm diameter) feeding a small pipes sector (200 mm and 300 mm diameter). Residence times range from 0 to 13.6 hours in main pipes and from 13.6 h to 18.4 h in small pipes. All pipes are made of steel or ductile iron and their interior is lined with concrete; there is therefore little corrosion. Since the raw water is of such high quality, the treatment plant is very simple: a direct filtration on sand followed by ozonation and chlorine disinfection. Samples were taken on 14 occasions, during a full year period, in the distribution system and in the treatment plant after chlorination. These last samples were incubated in clean flasks at the network temperature. Measurements of temperature, pH, disinfection by-products (trihalomethanes, aldehydes, haloacetonitriles, haloacetones and chloropicrine), total organic carbon (TOC), biodegradable dissolved organic carbon (BDOC) and number of bacteria (heterotrophic plate count and total direct count by epifluorescence) were completed.The distribution network seems to have very little effect on chlorine demand and disinfection by-products. Results from water incubated in flasks are similar to those from distribution network. After more than 18 hours contact time, the chlorine residual is still higher than 0.2 mg/l in most of the samples taken in the distribution network and in the flask. It should be noted that the initial chlorine concentrations range from 0.65 mg/l (cold water) to 1.00 mg/l (warm water). Chlorine demand and trihalomethane (THM) curves are typical, a rapid increase with time followed by a relatively stable level. THM concentrations in the distribution network are low: a typical value of 14 µg/l after 13.6 hours contact time is detected. The maximum concentration of 43 µg/l of total THM was measured in a dead end. In this latter sample, 42 % of the THM was present as bromodichloromethane and 39 % as chloroform. Other by-products such as haloacetonitrile, haloacetone and chloropicrine were always detected in very small concentrations.Aldehyde concentrations in treated water were low, between 21 and 42 µg/l. These concentrations were stable throughout the distribution system. Fixed and free biomass seems to have very little effect on these biodegradable compounds. These results were confirmed by BDOC results. BDOC in treated water ranges from 0.2 to 0.45 mg/l and remains stable in the distribution system. These low BDOC concentrations and the chlorine residual of approximately 0.2 mg/l seem to be sufficient to prevent regrowth in the distribution system. Total direct counts by epifluorescence showed almost no increase of bacterial density except for the July 11th sample. This is the only day where the free chlorine residual dropped below 0.2 mg/l, with values of free chlorine residual dropping as low as 0.16 mg/l