The Effects of Observation of Learn Units During Reinforcement and Correction Conditions on the Rate of Learning Math Algorithms by Fifth Grade Students

I conducted two studies on the comparative effects of the observation of learn units during (a) reinforcement or (b) correction conditions on the acquisition of math objectives. The dependent variables were the within-session cumulative numbers of correct responses emitted during observational sessions. The independent variables were the observation of reinforcement for correct responses as the control condition and the observation of corrections for incorrect responses. Eight 11-year-old target participants, 3 females and 5 males, were selected to participate in Experiment 1, during which a counterbalanced simultaneous treatment across participants design was used. Target participants and non-target peers were presented with math objectives that were not in repertoire. The non-target peers received feedback in the form of either reinforcement or a correction in 2 separate conditions while target students observed and received no feedback. Results from Experiment 1 showed that all of the target participants mastered the 3 math objectives presented during the observation of the correction condition and 7 of the 8 target participants mastered the objective during the reinforcement condition. Target participants met criterion with significantly fewer numbers of observing opportunities during the correction condition than during the reinforcement condition. Experiment 2 was a replication of Experiment 1 with greater experimental control. Six target participants, 4 females and 2 males, 10-year-olds, were selected to participate in Experiment 2, in which a between subjects counterbalanced reversal design across conditions and math objectives was implemented. Results showed that all target participants mastered 18 out of 18 math objectives presented during the correction condition and target participants mastered 10 out of 18 objectives presented during the reinforcement condition

Pedagogical Freedom through Hope: How Communication Centers Can Instill Actionable Hope through a K-12 Citizenship Education Model

This paper argues Communication Centers as a core space for revitalizing citizenship education through dialogic interaction and the encouragement of outside civic engagement. Developing informed and sustainable hope requires education (Lake, et al., 2012). Learning how to develop habits of hope can lead to students becoming more informed and civil citizens because it attunes students to their civic potential and enables them to cultivate visions for future democracies

An Ethical Revelation of the American Revolution: An Analysis of Communication Ethics and Hypertextuality in the Musical Hamilton

Since debuting in 2016, Hamilton has generated much scholarship on such topics as race relations and public memory. However, this article uses concepts of communication ethics and hypertextuality to situate the retelling of America’s past for America’s present. Connecting Hamilton to communication ethics proves paramount because it helps to situate the moral ground under which the characters stand, thereby serving as the epicenter for the show’s ultimate message. Viewers are brought into a hypertextual world of two historical moments, America ‘then’ and America ‘now,’ and consider the juxtaposition of past and current ideas, tradition, culture and narrative commitments that all result in an ethical climax as the main character, Alexander Hamilton champion’s an ethic of, “I am my brother’s keeper.

Tropical transport and the seasonal variability of the subtropical "edges" in the stratosphere

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, February 2001.Includes bibliographical references (p. 214-223).The chemistry of the stratosphere, in particular the balance between ozone production and loss, is very sensitive to transport into and out of the tropical stratosphere. There is a great deal of evidence that tropical air remains relatively isolated from extratropical air over timescales that are long compared to typical midlatitude mixing timescales. However, there are significant questions regarding the extent to which the tropics may be considered isolated, the mechanisms and variability of this isolation, and the implications of tropical isolation for global-scale transport. We address some of these issues using three very different tools: a simple model of stratospheric transport, which allows us to investigate the role of tropical transport in determining global transport timescales, satellite observations of long-lived tracers, which allow us to diagnose the seasonal variability of the tracer gradients that mark the transition between tropical and extratropical air, and a shallow water model, which allows us to investigate the mechanisms of tropical isolation in the simplest relevant dynamical framework. We first discuss the characteristics of analytical solutions for the mean age of air, a measure of the mean timescale for transport by large-scale processes in the stratosphere, in a simple, one-dimensional conceptual model of stratospheric transport. In this "leaky pipe" model, the stratosphere is divided into three regions: the tropics and the Northern and Southern extratropics. We examine the dependence of the mean age on advection, diffusive mixing, and quasi-horizontal transport between the tropics and the extratropics. This work provides insight into the role of the tropics in global chemical transport under the assumption of at least some degree of tropical isolation. We next examine the seasonal variability of the subtropical tracer gradients which mark the transition between tropical and extratropical air from both a diagnostic and a mechanistic standpoint. We use probability distribution functions of satellite measurements of long-lived tracers to define the transition regions, which are commonly called the subtropical "edges". We examine six and a half years of measurements and identify the central latitude, and in some cases the area, of these edges at eight pressure levels on quasi-monthly timescales. We compare the seasonal variability of the subtropical edges to the variability in several transport parameters and thus increase our understanding of the mechanisms of tropical isolation from a diagnostic standpoint. We then use a shallow water model, which represents many of the properties of the flow between two isentropic surfaces, to examine the mechanisms of the formation of the subtropical edges during each season. We include the effects of diabatic heating and cooling as well as planetary-scale wave propagation and examine the role of these processes in the formation of potential vorticity gradients that behave in much the same way as the observed subtropical tracer gradients. Our results indicate that the winter subtropical edge marks a mixing barrier. The rapid stirring in the winter hemisphere that results from planetary-scale wave breaking is generally confined to the midlatitudes, and the strong tracer and potential vorticity gradients in the winter subtropics likely result from "stripping" processes, as filaments of material are occasionally pulled out of the tropics by this mid-latitude stirring. The summer subtropical edge, however, does not mark a mixing barrier in the middle and upper stratosphere. Rather, it is likely that the strong subtropical tracer and potential vorticity gradients in the summer hemisphere result purely from the action of the residual circulation, which tends to increase potential vorticity and tracer values in the tropics and decrease them at high latitudes (for tracers with tropospheric sources and photochemical sinks) over the course of the summer. We show that the seasonal variability of the edges can, in some cases, contribute significantly to the mass budgets in simple "leaky pipe"-type models, but find that it is difficult to assess the role of this seasonal variability in tracer transport.by Jessica L. Neu.Ph.D

The strength of the meridional overturning circulation of the stratosphere.

The distribution of gases such as ozone and water vapour in the stratosphere - which affect surface climate - is influenced by the meridional overturning of mass in the stratosphere, the Brewer-Dobson circulation. However, observation-based estimates of its global strength are difficult to obtain. Here we present two calculations of the mean strength of the meridional overturning of the stratosphere. We analyze satellite data that document the global diabatic circulation between 2007- 2011, and compare these to three re-analysis data sets and to simulations with a state-of-the-art chemistry-climate model. Using measurements of sulfur hexafluoride (SF6) and nitrous oxide, we calculate the global mean diabatic overturning mass flux throughout the stratosphere. In the lower stratosphere, these two estimates agree, and at a potential temperature level of 460 K (about 20 km or 60 hPa in tropics), the global circulation strength is 6.3-7.6 × 109 kg/s. Higher in the atmosphere, only the SF6-based estimate is available, and it diverges from the re-analysis data and simulations. Interpretation of the SF6 data-based estimate is limited because of a mesospheric sink of SF6; however, the reanalyses also differ substantially from each other. We conclude that the uncertainty in the mean meridional overturning circulation strength at upper levels of the stratosphere amounts to at least 100 %

Impacts of global NOx inversions on NO2 and ozone simulations

Tropospheric NO2 and ozone simulations have large uncertainties, but their biases, seasonality, and trends can be improved with NO2 assimilations. We perform global top-down estimates of monthly NOx emissions using two Ozone Monitoring Instrument (OMI) NO2 retrievals (NASAv3 and DOMINOv2) from 2005 to 2016 through a hybrid 4D-Var/mass balance inversion. Discrepancy in NO2 retrieval products is a major source of uncertainties in the top-down NOx emission estimates. The different vertical sensitivities in the two NO2 retrievals affect both magnitude and seasonal variations of top-down NOx emissions. The 12-year averages of regional NOx budgets from the NASA posterior emissions are 37&thinsp;% to 53&thinsp;% smaller than the DOMINO posterior emissions. Consequently, the DOMINO posterior surface NO2 simulations greatly reduced the negative biases in China (by 15&thinsp;%) and the US (by 22&thinsp;%) compared to surface NO2 measurements. Posterior NOx emissions show consistent trends over China, the US, India, and Mexico constrained by the two retrievals. Emission trends are less robust over South America, Australia, western Europe, and Africa, where the two retrievals show less consistency. NO2 trends have more consistent decreases (by 26&thinsp;%) with the measurements (by 32&thinsp;%) in the US from 2006 to 2016 when using the NASA posterior emissions. The performance of posterior ozone simulations has spatial heterogeneities from region to region. On a global scale, ozone simulations using NASA-based emissions alleviate the double peak in the prior simulation of global ozone seasonality. The higher abundances of NO2 from the DOMINO posterior simulations increase the global background ozone concentrations and therefore reduce the negative biases more than the NASA posterior simulations using GEOS-Chem v12 at remote sites. Compared to surface ozone measurements, posterior simulations have more consistent magnitude and interannual variations than the prior estimates, but the performance from the NASA-based and DOMINO-based emissions varies across ozone metrics. The limited availability of remote-sensing data and the use of prior NOx diurnal variations hinder improvement of ozone diurnal variations from the assimilation, and therefore have mixed performance on improving different ozone metrics. Additional improvements in posterior NO2 and ozone simulations require more precise and consistent NO2 retrieval products, more accurate diurnal variations of NOx and VOC emissions, and improved simulations of ozone chemistry and depositions. </div

An atmospheric chemist in search of the tropopause

Delineating the boundary between troposphere and stratosphere in a chemistry transport model requires a state variable for each air mass that maps out the ever shifting, overlapping three-dimensional (3-D) boundary at each time step. Using an artificial tracer, e90, with surface sources and 90 day decay time, the model e90 tropopause matches the 1-D temperature lapse rate definition of the tropopause as well as the seasonal variation of ozone at this boundary. This approach works from equator to pole, over all seasons, unlike methods based on potential vorticity or ozone. By focusing on the time scales that separate stratosphere from troposphere, we examine the cause of ozone seasonality at the midlatitude tropopause, the oldest air in the troposphere (winter descent in the subtropics), and a north-south bias in the age of air of the lowermost stratosphere as evaluated using a northern tracer. The tracer e90 is invaluable in 3-D modeling, readily separating stratosphere from troposphere and a giving quantitative measure of the effective distance from the tropopause

Modeling Study of the Air Quality Impact of Record-Breaking Southern California Wildfires in December 2017

We investigate the air quality impact of record‐breaking wildfires in Southern California during 5–18 December 2017 using the Weather Research and Forecasting model with Chemistry in combination with satellite and surface observations. This wildfire event was driven by dry and strong offshore Santa Ana winds, which played a critical role in fire formation and air pollutant transport. By utilizing fire emissions derived from the high‐resolution (375 × 375 m²) Visible Infrared Imaging Radiometer Suite active fire detections, the simulated magnitude and temporal evolution of fine particulate matter (PM_(2.5)) concentrations agree reasonably well with surface observations (normalized mean bias = 4.0%). Meanwhile, the model could generally capture the spatial pattern of aerosol optical depth from satellite observations. Sensitivity tests reveal that using a high spatial resolution for fire emissions and a reasonable treatment of plume rise (a fair split between emissions injected at surface and those lifted to upper levels) is important for achieving decent PM_(2.5) simulation results. Biases in PM_(2.5) simulation are relatively large (about 50%) during the period with the strongest Santa Ana wind, due to a possible underestimation of burning area and uncertainty in wind field variation. The 2017 December fire event increases the 14‐day averaged PM_(2.5) concentrations by up to 231.2 μg/m³ over the downwind regions, which substantially exceeds the U.S. air quality standards, potentially leading to adverse health impacts. The human exposure to fire‐induced PM_(2.5) accounts for 14–42% of the annual total PM_(2.5) exposure in areas impacted by the fire plumes