372 research outputs found
The Relationship between infrastructure and regional economic growth: evidence from Mexico
Treballs Finals del MĂ ster d'Economia, Facultat d'Economia i Empresa, Universitat de Barcelona, Curs: 2020-2021, Tutor: GermĂ Bel & RaĂşl RamosThe relationship between physical infrastructure and economic growth has been investigated by many, with the direction and magnitude of the result depending on the data and the empirical model applied. This paper adds to the literature by addressing spatial heterogeneity and possible endogeneity in a panel of 32 Mexican states for the period 2005-2018, thus many limitations of earlier studies are overcome. First results indicate a U-shaped relationship with positive spillovers; however, robustness checks do not confirm these findings. Most evidence points towards infrastructure not having any significant impact on regional economic growth in Mexico
Critical Reflections on Teacher Conceptions of Race as Related to the Effectiveness of Science Learning
The Maker Movement’s current traction in education revolves around the notion that constructing artifacts improves student interest and engagement. Often touted as a new and important way for students to access STEM content, “making” activities offer a unique opportunity to disrupt the traditional perceptions of who can successfully “do” STEM. Blending familiar materials and practices (e.g. sewing with a needle and thread) with atypical materials (e.g., conductive thread and sewable LED bulbs), electronic textiles, or e-textiles, allow makers to create working circuits in ways that connect with their out-of-school lives, including heritage and vernacular cultural practices. This article describes the experiences of one student and one teacher as they explored e-textiles for the first time in their respective roles. Our student, a thirteen year-old Native American girl, reported a sense of empowerment and newfound engagement with science; she shares the ways in which she was able to incorporate multiple aspects of her identity into her project. On the other side of the experience, we examine the ways in which our teacher’s ideas and conceptions of the abilities of his ELLs shifted as he taught science using e-textiles. Our discussion highlights the importance of these self and other conceptual changes as a mechanism for broadening participation in STEM learning
Variations in the Intensity of Specialized Science, Technology, Engineering, and Mathematics (STEM) High Schools
Educators and policymakers in the United States advocate the development of specialized STEM (science, technology, engineering, and mathematics) schools, but little is known about the unique features and practices of these schools. Because no meaningful differences have been found attributable to model type (Tofel-Grehl & Callahan, 2014), the current study purposefully sampled 6 specialized STEM schools in the United States that provided different levels of STEM experiences for students related to highly varied goals and missions using a grounded theory approach. Schools were found to fall into two categories, high and low STEM intensity, based on five major traits. Schools categorized as “higher STEM intensity and focus” had students who reported a stronger interest in a future STEM career, offered substantially more high-level STEM classes, and retained a faculty with a higher number of terminal area content degrees compared to schools categorized as “lower STEM intensity.” Although there are significant common themes and programmatic themes and features among different STEM schools, substantial differences exist between the nature and intensity of the STEM experiences of schools. Categorizing STEM schools into higher and lower STEM experience intensity provides a useful mechanism for examining those differences. Students in schools with a higher STEM intensity appear to spend more time on the “doing” of science
Introduction to the Special Issue on Immunology
The COVID-19 pandemic laid bare the absence of needed resources for teachers to engage students in learning about infectious disease as both a socioscientific issue and a scientific phenomenon (Kafai et al. 2022). With infectious disease largely absent from the NGSS, teachers had to creatively link lessons that contextualized and examined key aspects of infectious disease education during the COVID-19 pandemic. We saw in real time the impacts of popular news, social media, and public mood on broader socioscientific behaviors such as vaccination, masking, and social distancing. We watched as people’s understanding of the nature of science (Lederman 2013) and its tentativeness played into behavior decisions to abide by mask mandates or social distancing requirements. Much of the fabric of the social contract that binds society was strained as folks grappled with a worldwide scientific event that dictated many facets of their daily life
Autonome Instrumentierung von Altbergbau durch einen mobilen Manipulator
Im Fokus dieser Arbeit steht die Konzeption, Entwicklung und Erprobung eines autonomen Roboters zur Instrumentierung eines untertägigen Bergwerks. Der exemplarische Anwendungsfall umfasst das selbstständige Absetzen intelligenter Sensorstationen durch einen Roboterarm. Der Roboter ist einer der ersten mobilen Manipulatoren für den langfristigen Einsatz unter Tage. Ziel ist es, die Sicherheit für den Bergmann zu erhöhen, indem in gefährlichen Situationen der mobile Manipulator als echte Alternative zur Verfügung steht. Das fordert von dem Roboter selbstständiges und adaptives Handeln in einer Komplexität, die mobile Manipulatoren bisher lediglich in strukturierten Umgebungen leisten. Exemplarisch dafür ist das Platzieren von Technik im Altbergbau - Dunkelheit, Nässe und enge Querschnitte gestalten dies sehr herausfordernd. Der Roboter nutzt seine anthropomorphe Hand, um verschiedene Objekte abzusetzen. Das sind im konkreten Fall Sensorboxen, die diese Arbeit für die Instrumentierung des Bergwerks vorschlägt. Wichtig ist, dass das Absetzen autonom geschieht. Der Roboter trifft die Entscheidungen, wo er etwas platziert, welche Trajektorie sein Arm wählt und welchen Planungsalgorithmus er nutzt, vollkommen selbstständig. In dem Zusammenhang entwirft diese Dissertation eine variable Absetzroutine. Der mobile Manipulator baut dafür ein Kollisionsmodell der Umgebung auf, sucht eine geeignete Absetzposition, greift ein vordefiniertes Objekt und platziert dies im Bergwerk. Sicherheit und Robustheit stehen dabei an vorderster Stelle. Entsprechend schließt die Absetzroutine nach dem Absetzen nicht ab, sondern führt eine unabhängige Überprüfung durch. Dabei vergleicht der mobile Manipulator über Sensoren die wahrgenommene mit der angestrebten Objektposition. Hier kommen auf Deep Learning basierende Methoden zum Einsatz, die eine Überprüfung auch in vollkommener Dunkelheit erlauben. In insgesamt 60 Experimenten gelingt das Absetzen in 97% der Fälle mit einer Genauigkeit im Zentimeterbereich. Dabei beschränkt sich diese Evaluierung nicht auf das untertägige Bergwerk, sondern wertet auch Experimente in strukturierten und offenen Umgebungen aus. Diese Breite erlaubt eine qualitative Diskussion von Aspekten wie: Autonomie, Sicherheit und Einfluss der Umgebung auf das Verfahren. Das Ergebnis ist die Erkenntnis, dass der hier vorgestellte Roboter die Lücke zwischen Untertagerobotern und den mobilen Manipulatoren aus Industrieanwendungen schließt. Er steht in gefährlichen Situationen als Alternative zur Verfügung.:Inhaltsverzeichnis
Abbildungsverzeichnis
Tabellenverzeichnis
AbkĂĽrzungsverzeichnis
Notation
Variablenverzeichnis
1. Einleitung
1.1. Motivation
1.2. Forschungsfrage und Beitrag der Arbeit
1.3. Aufbau der Arbeit
2. Forschungstrends bei mobilen Manipulatoren und Untertagerobotern
2.1. Mobile Manipulatoren in verschiedenen Einsatzszenarien
2.2. Wettbewerbe mobiler Manipulatoren und Trends im Forschungsgebiet
2.3. Hard- und Software Komponenten fĂĽr mobile Manipulatoren
2.4. Zusammenfassung
3. Aufbau von Julius - dem Roboter fĂĽr den Einsatz im Altbergbau
3.1. Umgebungsbedingungen im untertägigen Altbergbau
3.2. Physischer Aufbau des Roboters
3.3. Softwaretechnische Grundlagen fĂĽr ein autonomes Handeln
3.4. Zusammenfassung
4. Entwurf der autonomen Absetzroutine fĂĽr Julius
4.1. Planen von Armbewegungen
4.2. Umgebungsmodell detaillieren
4.3. Bodenfläche identifizieren
4.4. Absetzposition berechnen
4.5. SSB greifen
4.6. Absetzrotation festlegen
4.7. SSB absetzen
4.8. Absetzpose ĂĽberprĂĽfen
4.9. Zusammenfassung
5. Experimentelle Validierung von Julius und der Absetzroutine
5.1. Beschreibung des Experiments und der generellen Rahmenbedingungen
5.2. Referenzexperimente im Innenbereich
5.3. Experimente im AuĂźenbereich
5.4. Experimente im Forschungs- und Lehrbergwerk
5.5. Diskussion
5.6. Zusammenfassung
6. Zusammenfassung
6.1. Erkenntnisse dieser Arbeit
6.2. Fazit
6.3. Ausblick
Literatur
Anhang
A. Berechnung der Absetzrotation
B. Ăśbersicht technischer Daten
C. WeiterfĂĽhrende Abbildungen
D. Messdate
Potentially Electric: An E-Textiles Project as a Model for Teaching Electric Potential
Electric potential is one of the most challenging concepts taught in high school physics classes due to the abstract nature of the concept.1 When taught, electric potential is often taught using a poorly triangulated set of instructional analogies, each possessing different strengths and limitations. Within this paper we share our learning from a two-week electronic textiles (e-textiles) unit designed to help students in an AP high school physics course improve their understanding of electric potential through the construction of a project entitled “The Slouching T-shirt” (STS) (Fig. 1). The STS project was part of a larger instructional unit on electricity and energy that seeks to make connections between energy, electric potential, and computer programming central to student learning
Equitable Engagement in STEM: Using E-Textiles to Challenge the Positioning of Non-Dominant Girls in School Science
This paper examines how working with sewable, programmable electronics embedded in textiles (e-textiles) impacted the self-perceptions and actions of two middle school girls from non-dominant communities as they navigated their place within science class. Using analytic induction (Erickson, 1986), we explore the phenomena around their experiences and the influence of their teachers’ perceptions. Findings indicate that the personalizable nature of e-textiles created a meaningful opportunity for students to engage in science class in a new way
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