Institutional Repository

The UDSpace Institutional Repository collects and disseminates research material from the University of Delaware.

  • Faculty, staff, and graduate students can deposit their research material directly into UDSpace. Faculty may use UDSpace to fulfill the University of Delaware Faculty Senate Open Access Resolution, and in many cases may use it to fulfill open access requirements from grant funding agencies.
  • Departments can use UDSpace to publish or distribute their working papers, technical reports, or other research material.
  • UDSpace also includes all doctoral dissertations from winter 2014 forward, and all master's theses from fall 2009 forward.

To learn more about UDSpace, and how you can make your research openly accessible to the public, visit our UDSpace Policies website.

 

Recent Submissions

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Cosmic-Ray Flux Correlation between MCMU and JBGO Neutron Monitors
(The Astrophysical Journal, 2024-11-08) Kittiya, A.; Nuntiyakul, W.; Seripienlert, A.; Madlee, S.; Sonsrettee, W.; Evenson, P.; Ruffolo, D.; Sáiz, A.; Oh, S.; Jung, J.
Neutron monitors (NMs) are large ground-based detectors of atmospheric secondary particles, mostly neutrons, from primary cosmic rays. Their sky direction and rigidity imply a well-defined incoming (asymptotic) direction in space. From 2015 December 16 to 2017 January 8, 6 of the 18 NM counters had been transferred from McMurdo to Jang Bogo, both in Antarctica, so data from similar detectors were recorded simultaneously at these two nearby NM stations. Autocorrelations of these NM count rates are well fit as the sum of three components: an exponential function and a cosine with a period of 1 day, both centered at zero lag, plus a constant. Fitting the cross correlation of the two count rates, the functions are no longer centered at zero lag. The best-fit cosine phase is at time lag −160.22 ± 0.12 minutes. Calculating cosmic-ray trajectories in Earth's magnetic field throughout the time interval, the mean difference in response-weighted asymptotic longitudes corresponds to time lag −169.41 ± 0.31 minutes, in close agreement with the observed lag. Thus, the cosine term is consistent with and provides a technique to cleanly measure the cosmic-ray anisotropy. In contrast, the peak term shows a time lag of –14.55 minutes, much closer to the –9.60 minutes lag in rotation due to the difference in geographic longitude. We find a similar behavior in the correlations between other pairs of stations. We propose that rapid fluctuations in the counting rate may be primarily due to cosmic-ray particles of very high energy.
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Affordances of Media as Learning and Play: Children’s and Mothers’ Conceptions
(International Journal of Early Childhood, 2024-09-12) Dore, Rebecca A.; Preston, Marcia S.; Golinkoff, Roberta Michnick; Hirsh-Pasek , Kathy
Educational and playful forms of media are both pervasive in children’s media landscape. Children tend to see play and learning as distinct, whereas parents tend to recognize the overlap between these categories; however, little research investigates children’s and parents’ conceptions of media as learning or play. Children (N = 80, five- and seven-year-olds) and mothers (N = 40) were shown black-and-white line drawings representing a child engaging in both media and non-media activities and asked to categorize each image as learning/not learning and as play/not play. Both mothers and children were less likely to see media as learning than non-media activities. However, children were less likely than mothers to differentiate between media and non-media activities in their conceptions of play. Both mothers and children were less likely to conceive of media activities than non-media activities as both learning and play, but this effect was stronger for mothers. These results suggest that mothers may see media more negatively and/or instrumentally, whereas children may see media as one of many options for playtime, indicating that parents should be encouraged to see media in a playful light, alongside other non-digital options for childhood play. Résumé Les formes éducatives et ludiques de médias sont toutes deux omniprésentes dans le paysage médiatique des enfants. Les enfants ont tendance à considérer le jeu et l’apprentissage comme des notions distinctes, tandis que les parents ont tendance à reconnaître le chevauchement entre ces catégories. Cependant, peu de recherches examinent les conceptions des enfants et des parents des médias en tant qu’apprentissage ou jeu. Des enfants (N = 80, âgés de cinq et sept ans) et des mères (N = 40) ont vu des dessins au trait noir et blanc représentant un enfant participant à des activités médiatiques et non médiatiques et ont été invités à classer chaque image comme apprentissage/non-apprentissage et comme jeu/non-jeu. Les mères et les enfants étaient moins susceptibles de considérer les médias comme des activités d'apprentissage que les activités non médiatiques. Cependant, les enfants étaient moins susceptibles que les mères de faire la différence entre les activités médiatiques et non médiatiques dans leurs conceptions du jeu. Les mères et les enfants étaient moins susceptibles de concevoir les activités médiatiques que les activités non médiatiques à la fois comme un apprentissage et un jeu, mais cet effet était plus fort pour les mères. Ces résultats suggèrent que les mères peuvent voir les médias de manière plus négative et/ou instrumentale, tandis que les enfants peuvent voir les médias comme l'une des nombreuses options de jeu, ce qui indique que les parents devraient être encouragés à voir les médias sous un angle ludique, aux côtés d'autres options non numériques pour le jeu des enfants. Resumen Tanto los medios educativos como los lúdicos están muy extendidos en el panorama mediático infantil. Los niños tienden a ver el juego y el aprendizaje como algo distinto, mientras que los padres tienden a reconocer la superposición entre estas categorías; sin embargo, hay pocas investigaciones que investiguen las concepciones de los niños y los padres sobre los medios como aprendizaje o juego. Se mostraron a niños (N = 80, de cinco y siete años) y madres (N = 40) dibujos en blanco y negro que representaban a un niño participando en actividades mediáticas y no mediáticas y se les pidió que categorizaran cada imagen como aprendizaje/no aprendizaje y como juego/no juego. Tanto las madres como los niños tenían menos probabilidades de ver los medios como aprendizaje que las actividades no mediáticas. Sin embargo, los niños tenían menos probabilidades que las madres de diferenciar entre actividades mediáticas y no mediáticas en sus concepciones del juego. Tanto las madres como los niños tenían menos probabilidades de concebir las actividades mediáticas que las no mediáticas como aprendizaje y juego, pero este efecto fue más fuerte para las madres. Estos resultados sugieren que las madres pueden ver los medios de comunicación de forma más negativa y/o instrumental, mientras que los niños pueden verlos como una de las muchas opciones para el tiempo de juego, lo que indica que se debe alentar a los padres a ver los medios desde una perspectiva lúdica, junto con otras opciones no digitales para el juego infantil.
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Structural dynamics of PtSn/SiO2 for propane dehydrogenation
(Catalysis Science & Technology, 2024-07-24) Yu, Kewei; Scarpelli, Matthew; Sourav, Sagar; Worrad, Alfred; Boscoboinik, J. Anibal; Ma, Lu; Ehrlich, Steven N.; Marinkovic, Nebojsa; Zheng, Weiqing; Vlachos, Dionisios G.
PtSn bimetallic catalysts are among the best-performing propane dehydrogenation (PDH) catalysts. However, understanding these catalysts remains limited due to the intricate nature of bimetallic systems and their dynamic structural evolution under reaction conditions. To address this challenge, we employ various in situ/operando techniques, including UV-vis, CO diffuse reflective infrared Fourier transform spectroscopy (CO-DRIFTS), near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS), and operando X-ray absorption spectroscopy (XAS), to elucidate the structural dynamics of PtSn/SiO2 catalysts under reduction and working conditions. Our investigation reveals that the interactions between Pt, Sn, and SiO2 support are strongly influenced by the synthesis procedures and the initial catalyst structure. Exposure to H2 causes a reversible Sn–OH formation observed by modulation excitation spectroscopy (MES). A sequentially impregnated catalyst with a nominal Pt : Sn ratio of 1 : 3 and a co-impregnated catalyst with a ratio of 1 : 2 exhibit optimal performance for PDH. Despite distinct synthesis procedures and bulk structures, these two catalysts exhibit comparable surface properties and PDH performance, attributed to the dynamic migration of Sn species and formation of a Pt-rich metal surface under reductive atmospheres.
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Is Bedtime Media Use Good or Bad? A Competitive Analysis Between the Sleep Displacement Hypothesis and the Media Recovery Hypothesis
(Media Psychology, 2024-11-12) Ellithorpe, Morgan E.; Eden, Allison; Ulusoy, Ezgi; Wirz, Dominique; Grady, Sara
Bedtime media use is often maligned in research and pop culture. However, the evidence for the relationship between bedtime media use and sleep for adults has been mixed – sometimes sleep quality is negatively affected by media use, sometimes it is positively affected. Competing explanations include the sleep displacement hypothesis (i.e. media use leads to later sleep onset, less total sleep, and lower sleep quality) and the media recovery hypothesis (i.e. media use helps reduce stress, and this relaxation helps people fall and stay asleep). Two retrospective diary studies test these competing hypotheses in an undergraduate sample (n = 200) and a general population U.S. adult sample (n = 202). Overall, results provide more support for the sleep displacement hypothesis than for the media recovery hypothesis. However, some evidence suggests potential for positive relationships between media use and sleep. More work is needed to explicate the complicated relationship between bedtime media use and sleep.
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Infant Motor Milestones: Analysis of Content and Variability Among Popular Sources for Parents
(Pediatric Physical Therapy, 2024-10-08) Orlando, Julie M.; Cunha, Andrea B.; Namit, Samantha; Banoub, Abram; Alharbi, Bashayer M.; Lobo, Michele A.
Purpose: Evaluate the content and variability of infant motor milestone education provided to parents in popular sources. Methods: Sources were screened for inclusion, and their motor milestone content was coded. Descriptive and inferential analyses were performed. Results: Content from 241 websites, applications, and books was evaluated; 6984 motor milestones were extracted, representing 146 unique milestone codes across 14 categories. Books and applications had more milestone content than websites. There was variability in the milestones mentioned and their associated ages across the sources and relative to the American Academy of Pediatrics (AAP) and Centers for Disease Control and Prevention (CDC) content. Several frequently mentioned milestones were behaviors that facilitate early learning. Conclusions: There is variability among sources in the motor milestones they provide to parents of infants. The AAP and CDC content likely has some influence on the broader content available, but there is substantial deviation from the information they provide. WHAT THIS EVIDENCE ADDS Current evidence: Education about developmental milestones can positively impact parental knowledge and confidence and enhance discussions between parents and healthcare providers.1 In addition to health care providers, parents report commonly accessing popular sources, including internet searches, websites, books, and mobile applications (apps), to learn about child development.2-5 Gap in the evidence: Parents are more likely to encounter information about milestones than suggestions for play activities or toys when searching about infant milestones, development, and play in popular sources.5 Yet, the nature of this motor milestone content has not been previously studied. How does this study fill this evidence gap? This study comprehensively describes which infant motor milestones parents are educated about by popular sources (ie, apps, books, and websites) and when those milestones are mentioned throughout infants’ first year of life. The study also evaluates whether the content available among popular sources besides those authored by the American Academy of Pediatrics (AAP) and the Centers for Disease Control and Prevention (CDC) varies from the information provided by the AAP and CDC. Implication of all the evidence: There is a large amount of variable information about infant’s motor milestones available to parents in popular sources, with similarities but also deviations and expansions from the AAP and CDC content. The results provide a comprehensive picture of the motor milestones that parents are likely to encounter in popular sources from birth through 1 year. They highlight behaviors parents are less likely to learn about on their own, suggesting health care providers might consider more active education if they want parents to be knowledgeable about these behaviors. Health care providers might suggest apps or books to parents seeking greater amounts of information yet may consider offering education periodically in concurrence with expected developmental skills.6