Introduction: The challenge of optimum integration of propulsion systems and large space structures

A functional matrix of possible propulsion system characteristics for a spacecraft for deployable and assembled spacecraft structures shows that either electric propulsion or low thrust chemical propulsion systems could provide the propulsion required. The trade-off considerations of a single propulsion engine or multiengines are outlined and it is shown that a single point engine is bounded by some upper limit of thrust for assembled spacecraft. The matrix also shows several additional functions that can be provided to the spacecraft if a propulsion system is an integral part of the spacecraft. A review of all of the functions that can be provided for a spacecraft by an integral propulsion system may result in the inclusion of the propulsion for several functions even if no single function were mandatory. Propulsion interface issues for each combination of engines are identified

Learning About Teachers’ Literacy Instruction From Classroom Observations

The purpose of this study is to contribute to efforts to improve methods for gathering and analyzing data from classroom observations in early literacy. The methodological approach addresses current problems of reliability and validity of classroom observations by taking into account differences in teachers’ uses of instructional actions (e.g., modeling) in specific skill areas (e.g., fluency, reading comprehension). The findings from observations of second‐ and third‐grade teachers’ literacy instruction showed that teachers’ instructional actions differed by literacy skill area and were more consistent within than across skill areas. Furthermore, teachers’ uses of instructional actions in a given skill area were more strongly associated with students’ gains in achievement in that skill area than were teachers’ uses of actions across all skill areas. The approach offers significant improvements in methods to identify features of effective literacy instruction. 本研究旨在改善早期读写教学课堂观察研究的资料蒐集方法和分析方法。这方法学研究针对当前有关课堂观察的可靠性和有效性问题,并考虑到教师在一些特定技能领域(例如,流畅度、阅读理解)方面所采取不同教学行动(例如,示范)上的差异。从二和三年级教师的读写教学课堂观察所得的研究结果显示,教师在教授不同读写技能时,其教学行动是有所差异的,而他们的教学行动,在各读写技能领域内的一致性却比跨读写技能领域的一致性较高。此外,教师在某一读写技能领域内所采用的教学行动,与学生在该技能上所取得的进步成绩有较强的关联,而在跨技能领域所采用的教学行动,与学生在这些技能上所取得的进步成绩的关联则较弱。这研究方法能识别出有效读写教学的特点,显著地改进了这方面研究的资料蒐集方法和分析方法。 El propósito de este estudio es contribuir a los esfuerzos de mejorar los métodos de recoger y analizar información de las observaciones de clases de alfabetización temprana. El acercamiento metodológico aborda los problemas recientes de confiabilidad y validez de las observaciones de clases tomando en cuenta las diferencias entre las acciones de adiestramiento (por ejemplo, modelar) que los maestros usan en áreas específicas de destrezas (por ejemplo, fluidez, comprensión de lectura). Los hallazgos de las observaciones de la instrucción de alfabetización de maestros de segundo y tercer grado mostraron que las acciones de adiestramiento de los maestros eran diferentes dependiendo del área de destreza y eran más constantes dentro de áreas de destreza que a través de ellas. Además, el uso de acciones de adiestramiento de los maestros en cualquier destreza específica se asociaba más con el mejoramiento de los estudiantes en dicha destreza que en sus acciones de adiestramiento a través de todas las áreas. Este acercamiento ofrece mejoras considerables en los métodos para identificar elementos de la instrucción efectiva. تهدف هذه الدراسة إلى مساهمة الجهود الرامية إلى تحسين طرق جمع المعطيات وتحليلها المأخوذة من ملاحظات غرفة الصف في التعلم المبكر. ويعالج هذا المدخل المنهاجي المشاكل الجارية بصدد ثبات ملاحظات غرفة الصف وصدقها من خلال مراعاة الاختلافات في أنشطة المعلمين التعليمية (مثل تقليد السلوك) في مجالات معينة (مثل مرونة القراءة والاستيعاب). وقد بينت نتائج الملاحظات من تعليم معرفة القراءة والكتابة لدى معلمي الصفين الثاني والثالث أن أنشطة المعلمين التعليمية اختلفت حسب مجال مهارة التعلم وكانت أكثر تطابقاً ضمن مجالات المهارات من عبرها. وبالإضافة إلى ذلك، حظت استخدامات الأنشطة التعليمية لدى المعلمين في مجال مهارة معين بأكثر ترابطاً مع تقدمات الطلاب في الإنجاز في مجال المهارة هذا من استخدامات الأنشطة لدى المعلمين عبر كل مجالات المهارة. توفر هذه الطريقة تحسنات ملحوظة فيما يتعلق بالطرق لتعيين معالم تعليم معرفة القراءة والكتابة الفعالة. Цeль иccлeдoвaния – дoпoлнить и coвepшeнcтвoвaть cyщecтвyющиe мeтoды cбopa и aнaлизa дaнныx o cтaнoвлeнии гpaмoтнocти. Для peшeния пpoблeм вaлиднocти и нaдeжнocти дaнныx, пoлyчaeмыx в пpoцecce нaблюдeний нa ypoкax, пpeдлaгaeтcя мeтoд, yчитывaющий paзличия в yчeбныx дeйcтвияx yчитeлeй (нaпpимep, мoдeлиpoвaния) пpи paзвитии oпpeдeлeнныx нaвыкoв (нaпpимep, бeглocти чтeния или пoнимaния пpoчитaннoгo). Peзyльтaты нaблюдeний зa yчитeлями втopыx и тpeтьиx клaccoв пoкaзaли, чтo для paзвития paзныx нaвыкoв yчитeля иcпoльзyют caмыe paзныe yчeбныe дeйcтвия, oднaкo, paзвивaя oдин и тoт жe нaвык, oни дeйcтвyют cxoдным oбpaзoм. Кpoмe тoгo, дeйcтвия yчитeлeй, cвязaнныe в coзнaнии yчeникoв c oпpeдeлeнным нaвыкoм, бoлee знaчимы, чeм дeйcтвия, кoтopыe oни пpимeняют пpи cтaнoвлeнии цeлoгo pядa paзличныx нaвыкoв. Дaнный пoдxoд cyщecтвeннo coвepшeнcтвyeт мeтoды для oпpeдeлeния нaибoлee эффeктивнoгo oбyчeния гpaмoтнocти. Cette étude a pour but de contribuer aux efforts réalisés pour améliorer le recueil et l'analyse des données provenant des observations relatives à l'entrée dans l’écrit. L'approche méthodologique présentée concerne les problèmes courants de fidélité et de validité des observations faites en classe, en prenant en compte les différences d'utilisation par le maître de ses interventions pédagogiques (par exemple, recourir à un modèle) dans des domaines de compétence bien définis (par exemple, la lecture courante, la compréhension de la lecture). Il est apparu, dans des observations de la littératie en 2 e et 3 e année, que les interventions pédagogiques des enseignants ne sont pas les mêmes selon la compétence en littératie considérée et qu'elles sont plus constantes pour un domaine donné que d'un domaine à l'autre. De plus, les interventions pédagogiques des enseignants dans un domaine de compétence donné sont liées plus fortement aux progrès des élèves dans ce domaine de compétence qu'aux interventions pédagogiques des maîtres dans l'ensemble des domaines de compétence. Cette approche propose des améliorations significatives dans les méthodes visant à identifier les caractéristiques d'un enseignement efficace de la littératie.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98775/1/rrq51.pd

Trajectory-Based Dynamic Map Labeling

In this paper we introduce trajectory-based labeling, a new variant of dynamic map labeling, where a movement trajectory for the map viewport is given. We define a general labeling model and study the active range maximization problem in this model. The problem is NP-complete and W[1]-hard. In the restricted, yet practically relevant case that no more than k labels can be active at any time, we give polynomial-time algorithms. For the general case we present a practical ILP formulation with an experimental evaluation as well as approximation algorithms.Comment: 19 pages, 7 figures, extended version of a paper to appear at ISAAC 201

Students’ Perspectives of Experiential Learning in an Addictions Course

Substance use disorder practitioners may identify as individuals in recovery, while others may have never experienced the challenge of abstinence. Without this lived experience, it may be difficult to accurately empathize with clients in recovery. Experiential learning is a way for students to live through an exercise in abstinence. The value of utilizing experiential learning for skill development and application of theory is established. However, there is no empirical research examining the use of experiential learning with undergraduate substance use disorder practitioner trainees not in recovery from addiction as a means to increase their ability to empathize with clients’ experiences. This article explored the impact of an experiential learning assignment in an undergraduate addictions course. A qualitative analysis of students’ written reflections revealed four primary themes. Authors offer suggestions for substance use disorder educators and recommendations for future research

Talking about food choices of former homeless young people: making sense of conflicting discourses of blame through social worlds theory.

After a pilot study at a charitable youth organisation in the North East of Scotland found no considerable improvements in the food choices of former homeless young people accommodated by the organisation (Perry, 2013), the Foodways and Futures project (2013-2016) set out to explore why. Both members of staff at the same organisation as well as young people were invited to voice their views and opinions on the factors influencing young people’s food choices. Whilst everyone’s contribution was considered equally informative for our findings, I was attentive to where the information originated from. In this, I found that three conflicting discourses of blame pervade the participants’ expressions of the rationales underlying young people’s food choices. Trying to make sense of these, I employ Strauss’ Social Worlds Theory (1978). I find that the different discourses of blame make sense in the context of the complex organisational structures. In objecting to a tendency in the literature to assign standardised discourse of blame primarily to youth workers’ practice, these discourses showcase mutual understanding instead

Predicting Second and Third Graders' Reading Comprehension Gains: Observing Students' and Classmates Talk during Literacy Instruction using COLT.

This paper introduces a new observation system that is designed to investigate students' and teachers' talk during literacy instruction, Creating Opportunities to Learn from Text (COLT). Using video-recorded observations of 2nd-3rd grade literacy instruction (N=51 classrooms, 337 students, 151 observations), we found that nine types of student talk ranged from using non-verbal gestures to generating new ideas. The more a student talked, the greater were his/her reading comprehension (RC) gains. Classmate talk also predicted RC outcomes (total effect size=0.27). We found that 11 types of teacher talk ranged from asking simple questions to encouraging students' thinking and reasoning. Teacher talk predicted student talk but did not predict students' RC gains directly. Findings highlight the importance of each student's discourse during literacy instruction, how classmates' talk contributes to the learning environments that each student experiences, and how this affects RC gains, with implications for improving the effectiveness of literacy instruction