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22 results on '"Dang, Steven"'

1. Convolutional neural networks applied to differential dynamic microscopy reduces noise when quantifying heterogeneous dynamics

Author

Martinez, Gildardo, Siu, Justin, Dang, Steven, Gage, Dylan, Kao, Emma, Avila, Juan Carlos, You, Ruilin, and McGorty, Ryan

Subjects
Condensed Matter - Soft Condensed Matter
Abstract

Differential dynamic microscopy (DDM) typically relies on movies containing hundreds or thousands of frames to accurately quantify motion in soft matter systems. Using movies much shorter in duration produces noisier and less accurate results. This limits the applicability of DDM to situations where the dynamics are stationary over extended times. Here, we investigate a method to denoise the DDM process, particularly suited to when a limited number of imaging frames are available or when dynamics are quickly evolving in time. We use a convolutional neural network encoder-decoder (CNN-ED) model to reduce the noise in the intermediate scattering function that is computed via DDM. We demonstrate this approach of combining machine learning and DDM on samples containing diffusing micron-sized colloidal particles. We quantify how the particles' diffusivities change over time as the fluid they are suspended in gels. We also quantify how the diffusivity of particles varies with position in a sample containing a viscosity gradient. These test cases demonstrate how studies of non-equilibrium dynamics and high-throughput screens could benefit from a method to denoise the outputs of DDM.

Published
2024
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2. Effect of a Novel Ergonomic Sheath on Dental Device-Related Muscle Work, Fatigue and Comfort-A Pilot Clinical Study.

Author

Dang, Steven, Wink, Cherie, Yang, Susan, Lin, Kairong, Takesh, Thair, Habib, Ali, and Wilder-Smith, Petra

Subjects
dental hygienist, dentist, electromyography, ergonomic sheath, ergonomics, micromotor, musculoskeletal disorder, ultrasonic scaler
Abstract

Background: Dental instrumentation with hand-held devices is associated with discomfort, fatigue and musculoskeletal diseases or repetitive stress injuries. The goal of this in vivo study was to determine the effect of an ergonomic handle sheath on muscle work, comfort and fatigue associated with (a) piezoelectric scaling by hygienists with and without musculoskeletal disorders (MSDs), and (b) dental cavity preparation by healthy dentists using a dental micromotor. Materials and Methods: Two groups of ten hygienists each tested the piezoelectric scaler. Hygienists in Group 1 had no MSDs, while those in Group 2 had been diagnosed with MSDs. Additionally, ten dentists with no MSDs used a dental micromotor to prepare four standardized cavities. Time-based work in four muscles, comfort and fatigue were recorded in the presence and absence of an add-on soft, insulating handle sheath. Data were analyzed using a repeated measures analysis of variance model with Tukeys post-hoc test. Results: Comfort, fatigue and muscle work were significantly better for both devices when the sheath was used. While hygienists with MSDs used more muscle work to complete the set scaling task, and the sheath-related reduction in work was somewhat greater, these MSD-related differences did not quite reach significance. Conclusions: The results of this pilot study show that the ergonomic performance of an ultrasonic scaler and a dental micromotor may be improved by the use of an ergonomic handle sheath.

Published
2024

3. Item Response Theory-Based Gaming Detection

Author

Huang, Yun, Dang, Steven, Richey, J. Elizabeth, Asher, Michael, Lobczowski, Nikki G., Chine, Danielle, McLaughlin, Elizabeth A., Harackiewicz, Judith M., Aleven, Vincent, and Koedinger, Kenneth

Abstract

Gaming the system, a behavior in which learners exploit a system's properties to make progress while avoiding learning, has frequently been shown to be associated with lower learning. However, when we applied a previously validated gaming detector across conditions in experiments with an algebra tutor, the detected gaming was not associated with learning, challenging its construct validity. Our iterative exploratory data analysis suggested that some contextual factors that varied across and within conditions might contribute to this lack of association. We present a latent variable model, "item response theory-based gaming detection" (IRT-GD), that accounts for contextual factors and estimates latent gaming tendencies as the degree of deviation from normative behaviors across contexts. Item response theory models, widely used in knowledge assessment, account for item difficulty in estimating latent student abilities: students are estimated as having higher ability when they can get harder items correct than when they only get easier items correct. Similarly, IRT-GD accounts for contextual factors in estimating latent gaming tendencies: students are estimated as having a higher gaming tendency when they game in less commonly gamed contexts than when they only game in more commonly gamed contexts. IRT-GD outperformed the original detector on three datasets in terms of the association with learning. IRT-GD also more accurately revealed intervention effects on gaming and revealed a correlation between gaming and perceived competence in math. Our approach is not only useful for others wanting to apply a gaming assessment in their context but is also generally applicable in creating robust behavioral measures. [For the full proceedings, see ED623995.]

Published
2022

6. The Ebb and Flow of Student Engagement: Measuring Motivation through Temporal Pattern of Self-Regulation

Author

Dang, Steven C. and Koedinger, Kenneth R.

Abstract

Effective teachers recognize the importance of transitioning students into learning activities for the day and accounting for the natural drift of student attention while creating lesson plans. In this work, we analyze temporal patterns of gaming behaviors during work on an intelligent tutoring system with a broader goal of detecting temporal trends in students' motivation. Findings demonstrate that observing gaming the system behaviors in the near beginning or end of a working session correspond with predictions made by self-regulation theories of ego-depletion and task-switching. Furthermore, analyses provide initial evidence these gaming behaviors are indicative of partial cognitive engagement and session-level influences on student motivation. These findings provide evidence for how temporal fluctuations in students motivations might be inferred through self-regulated behaviors like gaming the system, and how such information could inform better more intelligent tutoring systems that are responsive to cognitive and motivational dynamics during student work. [For the full proceedings, see ED607784.]

Published
2020

7. Core-shell droplets and microcapsules formed through liquid-liquid phase separation of a colloid-polymer mixture

Author

Dang, Steven, Brady, John, Rel, Ryle, Surineni, Sreenidhi, O'Shaughnessy, Conor, and McGorty, Ryan

Subjects
Condensed Matter - Soft Condensed Matter
Abstract

Microcapsules allow for the controlled containment, transport, and release of cargoes ranging from pharmaceuticals to fragrances. Given the interest from a variety of industries in microcapsules and other core-shell structures, a multitude of fabrication strategies exist. Here, we report on a method relying on a mixture of temperature-responsive microgel particles, poly(N-isopropylacrylamide) (pNIPAM), and a polymer which undergo fluid-fluid phase separation. At room temperature this mixture separates into colloid-rich (liquid) and colloid-poor (gas) fluids. By heating the sample above a critical temperature where the microgel particles shrink dramatically and develop a more deeply attractive interparticle potential, the droplets of the colloid-rich phase become gel-like. As the temperature is lowered back to room temperature, these droplets of gelled colloidal particles reliquefy and phase separation within the droplet occurs. This phase separation leads to colloid-poor droplets within the colloid-rich droplets surrounded by a continuous colloid-poor phase. The gas/liquid/gas all-aqueous double emulsion lasts only a few minutes before a majority of the inner droplets escape. However, the colloid-rich shell of the core-shell droplets can solidify with the addition of salt. That this method creates a core-shell structures with a shell composed of stimuli-sensitive microgel colloidal particles using only aqueous components makes it attractive for encapsulating biological materials and making capsules that respond to changes in, for example, temperature, salt concentration, or pH.

Published
2021

8. Exploring the Link between Motivations and Gaming

Author

Dang, Steven and Koedinger, Ken

Abstract

A student's ability to regulate their thoughts, emotions and behaviors in the face of temptation is linked to their task specific motivational goals and dispositions. Behavioral tasks are designed to strain a targeted resource to differentiate individuals through measures of their performance. In this paper, we explore how student behavior on differentially gamed learning material relates to estimates of student motivational goals and dispositions. We leverage observations of students in two different courses using an intelligent tutoring system over an entire academic year. We use a previously validated heuristic model of gaming detection to label instances of gaming. Each student's tendency to game is estimated separately using highly gamed and non-highly gamed sections of the course. Each estimate of student gaming is compared to precourse self-reported measures of student motivations. Results indicate that in naturalistic settings, gaming on more challenging materials is less influenced by student motivations and potentially a result of adaptive learning behaviors. Similarly, student gaming estimates using only non-highly gamed material are significantly related to all targeted motivation measures. Implications and future directions are discussed. [For the full proceedings, see ED599096.]

Published
2019

12. Exploring the Human Fabric through an Analyst’s Eyes

Author

Belov, Nadya, Patti, Jeff, Wilcox, Saki, Almanzar, Rafael, Kim, Janet, Kellogg, Jennifer, Dang, Steven, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Chai, Sun-Ki, editor, Salerno, John J., editor, and Mabry, Patricia L., editor

Published
2010
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19. IdeaGens

Author

Chan, Joel, primary, Dang, Steven, additional, and Dow, Steven P., additional

Published
2016
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21. Creating cosmopolis : the end of mainstream

Author

Dang, Steven R.

Abstract

Increasing cultural globalisation and the assertion of cultural identities present an interesting opportunity for cities in the postmodern Western World. An increasingly multi-situated polity must better reflect and serve an increasingly self-aware and heterogeneous population in search of better planning, community and social justice. A great deal of research in diversity issues has been conducted in various disciplines, but there is little integration of this theory and even less instruction as to its application. This thesis attempts to address the deficiencies - providing some rationale and some guidance towards the diversification of civic culture as a model of incorporation. Diversification requires a significant shift in our understanding of culture, identity, community and self - an end to mainstream and its hegemony. It places the onus for change on local institutions and operates on an assumption of difference, a desire for meaningful incorporation and a commitment to equality as equity. These principles translate into the pursuit of increasingly differentiated benefits, inclusive participation, varied discourse and inclusive definitions. For the transformation to be truly meaningful and systemic, it must take place in all agencies of civic culture: government, civil society, business, the media and family. A conceptual, prescriptive and evaluative framework for cultural diversification is thus elaborated. Change will require deliberate purpose and action. This thesis attempts to provide some direction by applying the discussion to a level at which most urban leaders, planners and cultural producers work. A local organisation in Vancouver, Canada - a reputed leader in diversity - is selected as a case to illustrate application of the developed framework and to enrich it with an initial investigation of how practitioners work towards the diversification of their individual institutions and their larger socio-cultural environment. It is hoped that strategies learned here, and in future applications of this research, can provide guidance for other organisations and that numerous small efforts will be rewarded with the gradual transformation of the whole.

Published
2002
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