Astronomy for Educators

Astronomy for Educators provides new and accomplished K-12 instructors with concepts and projects for low-cost, high-impact STEM classroom instruction that is built around the National Academies National Research Council\u27s K-12 Framework for Science Education.https://scholarworks.uark.edu/oer/1001/thumbnail.jp

On the Virialization of Disk Winds: Implications for the Black Hole Mass Estimates in AGN

Estimating the mass of a supermassive black hole (SMBH) in an active galactic nucleus (AGN) usually relies on the assumption that the broad line region (BLR) is virialized. However, this assumption seems invalid in BLR models that consists of an accretion disk and its wind. The disk is likely Keplerian and therefore virialized. However, the wind material must, beyond a certain point, be dominated by an outward force that is stronger than gravity. Here, we analyze hydrodynamic simulations of four different disk winds: an isothermal wind, a thermal wind from an X-ray heated disk, and two line-driven winds, one with and the other without X-ray heating and cooling. For each model, we check whether gravity governs the flow properties, by computing and analyzing the volume-integrated quantities that appear in the virial theorem: internal, kinetic, and gravitational energies, We find that in the first two models, the winds are non-virialized whereas the two line-driven disk winds are virialized up to a relatively large distance. The line-driven winds are virialized because they accelerate slowly so that the rotational velocity is dominant and the wind base is very dense. For the two virialized winds, the so-called projected virial factor scales with inclination angle as $1/ \sin^2{i}$. Finally, we demonstrate that an outflow from a Keplerian disk becomes unvirialized more slowly when it conserves the gas specific angular momentum -- as in the models considered here, than when it conserves the angular velocity -- as in the so-called magneto-centrifugal winds.Comment: Accepted to Ap

Exploring reading profiles of rural school students

This study investigates the reading profiles of rural Grade 5 and 6 students (N = 262), a sample with a high proportion of English language learners. We administered a battery of reading and cognitive assessments to classify students’ reading profiles and evaluate if performance on cognitive measures predicted membership in particular profiles. Data were analyzed using latent profile analysis. Latent profile analysis showed four distinct reading profiles in our sample: students with severe reading disabilities (< 2%), students at high risk of reading disability (14%), students at some-risk of reading disability (46%), and students who are typical readers (38%). Lower performance on cognitive measures was associated with group membership in the severe reading profile group compared to the group of students at some-risk of reading failure. In contrast, higher performance on cognitive measures was associated with group membership in the typical reader group compared to students at some-risk of reading failure. In keeping with the findings from past studies documenting reader profiles, we found heterogeneity in the reading profiles of rural upper-elementary grade students. We discuss the need for multicomponent interventions that target all areas of reading with some flexibility in the dosage of each reading component dependent on the reader profiles established prior to intervention

How Digital Divide affects Public E-Services: The Role of Migration Background

After the private sector the public sector also tries to benefit from the advantages of electronic service delivery, in particular from lower costs and higher service quality. While more and more services are available electronically, resident behind. But high usage rates and therefore a maximized potential target group, covering major parts of society, are essential prerequisite for successful public e-services. If the residents are not using the newly created electronic services, neither they benefit from better service quality nor do the public service provider save money. Digital divide research can be leveraged to maximize the potential target group of public e-service. For this purpose a focus on public e-services as level of analysis is required, since Internet access or regular Internet usage are necessary but no sufficient conditions for being able to use public e-services. This study employs qualitative research methods in an exploratory case study design to analyze the influence of migration background on the capability to use public e-services. It provides two testable propositions for further confirmatory research: Due to limited language skills and different cultural experiences, for residents with migration background Internet experience does not directly translate into confidence in their own public e-service skills

Which Processes Do Users Not Want Online? - Extending Process Virtualization Theory

Following the advent of the Internet more and more processes are provided virtually, i.e., without physical interactions between involved people and objects. For instance, E-Commerce has virtualized shopping processes since products are bought without physical inspection and interaction with sales staff. This study is founded on the key idea of process virtualization theory (PVT) that from the users’ perspective not all processes are equally amenable for virtualization. We investigate characteristics of processes, which are causing users’ resistance toward the virtualized process. Surveying 501 individuals regarding 10 processes, this study constitutes the first quantitative test evaluating the prediction capabilities of PVT by analysis of varying processes. Moreover, it introduces and successfully tests the extended PVT (EPVT), which integrates PVT with multiple, related constructs from extant literature in a unified model with multi-order causal relations. Thereby, it clearly enhances our understanding of human behavior with regard to the frequent phenomenon process virtualization

In Defense of Fair Value: Weighing the Evidence on Earnings Management and Asset Securitizations

Dechow, Myers, and Shakespeare (DMS, 2009) find a negative relation between income from securitization activities and income from non-securitization activities. DMS interprets this finding as indicating that managers use the flexibility available in fair value accounting rules to smooth earnings. We clarify the role of fair value in accounting for asset securitizations, discuss alternative explanations for the evidence presented in DMS, and offer suggestions for future research. We caution against inferring the desirability of any particular accounting method from earnings management research

Analytical calculation of the frequency-dependent litz wire resistance considering the wire connectors

Eddy-current effects have an impact on the resistance of litz wire. They reduce the utilization of the wire cross section. In a certain parameter range, the dominant influencing factor is the current distribution in the wire connectors. The connector itself does not significantly contribute to the wire resistance but it results in an inhomogeneous current distribution among the strands. We quantify the resistance increase by introducing a connector skin-effect factor and give a mathematical derivation. Taking the twisting of the strands into account requires a probabilistic model of the radial strand position. Resistance measurement results validate the calculation approach. We discuss the assumptions and derive the parameter range where the model is valid

Multicomponent Reading Intervention: A Practitioner's Guide

Discover the effective approach of multicomponent reading interventions, a personalized approach to support elementary grade students with reading difficulties. Explore how teachers can combine word reading, fluency, and comprehension to empower students' reading journey. M s. Patel, the dedicated special education teacher, gathers her Grade 4 students with reading difficulties for their small-group session. She has been diligently implementing phonics instruction, and she observes that the students are making strides in reading monosyllabic words. However, she also notices that their progress in tackling multisyllabic words has hit a roadblock. Additionally, they still require support in comprehending the meaning of the text, and their reading fluency remains laborious. Determined to find effective solutions, Ms. Patel recently came across the concept of multicom-ponent reading interventions. Excited about its potential benefits, she decides to introduce this approach to her small group. Her plan involves targeting multiple reading-related skills simultaneously during each session, with the aim of accelerating her students' reading progress. With enthusiasm and dedication, Ms. Patel sets out to design and implement the multicomponent intervention

Metapher

Verwendung des Begriffs 'Metapher' in verschiedenen Fachdiskursen

Mathematische Methoden für die effiziente Auslegung und den Betrieb induktiver Batterieladesysteme

Ein induktives Ladesystem mit hoher Übertragungsleistung, hohem Wirkungsgrad, Flexibilität in der Fahrzeugpositionierung, Fremdobjekterkennung, geringen elektromagnetischen Emissionen und sicherer Datenübertragung ist bei gleichzeitig geringem Bauraum sehr kostenintensiv. In dieser Arbeit wird der Entwicklungsprozess des Leistungsteils eines induktiven Ladesystems mit der Konzeption, der Auslegung, der Simulation und der Betriebsstrategie behandelt. Die entwickelten Spulensysteme werden in ein leistungselektronisches System eingebettet, das mit möglichst wenigen Komponenten realisiert wird, um Platz und Materialkosten zu sparen. Dazu gehört auch das Prinzip, auf aufwändige Messtechnik zu verzichten und diese durch Berechnungen zu ersetzen. Die Bereitstellung mathematischer Methoden ist themenübergreifend ein zentraler Beitrag dieser Arbeit. Für die effiziente Auslegung der Spulen, die Modellierung und die Zustandserfassung im Betrieb werden eigene Berechnungsverfahren vorgestellt. Durch Experimente werden diese in einem realitätsnahen Szenario verifiziert