1,220 research outputs found
A fast acting electrical servo for the actuation of full span, Fowler-type wing flaps in DLC applications: A detail design study
The philosophy and detail design of an electro-mechanical actuator for Fowler-type wing flaps which have a response time constant of 0.025 seconds are described. A conventional electrical servomotor with a power rating twice the maximum power delivered to the load is employed along with adaptive, gain-scheduled feedback and various logic circuits, including one to remove electrical excitation from the motor during extended periods when no motion of the flap is desired
Christmas Island rock phosphate in poultry feeding trials
In Western Australia, increasing quantities of ground rock phosphate from Christmas Island are being incorporated in stock foods to increase the calcium and phosphorus content. In a previous article (Snook 1958) experiments are reported which indicate that this particular rock phosphate can be incorporated in the rations of laying hens without any apparent effect on the health or productivity of the birds
School Science Capacity: A Study of Four Urban Catholic Grade Schools
Working from the view of schools as a system, and of school improvement as an ongoing journey (Hallinger & Heck, 2011; Jackson, 2000), this study investigated the perspectives of teacher leaders and principals from four metropolitan Catholic grade schools engaged in efforts to improve their school science programs. Built upon existing conceptualizations of school capacity, a model of school science capacity is presented and used as a framework for the development of four case studies. Findings gleaned from collecting and analyzing reports of teacher leaders’ and principals’ interpretations of their school systems illustrate how elements of the school science capacity framework interacted to support and at times constrain, the schools’ science improvement efforts. Implications for Catholic school educators, administrators, and researchers who seek to make science a priority, and build school science capacity, are discussed.
Capacité scientifique à l’école : une étude menée dans quatre écoles primaires catholiques en milieu urbain
Partant du concept que les écoles constituent un système et que leur amélioration est une quête perpétuelle (Hallinger & Heck, 2011; Jackson, 2000), cette enquête étudie sur les points de vue des responsables enseignants et chefs d’établissement de quatre écoles secondaires catholiques métropolitaines qui ont entrepris d’améliorer les programmes scientifiques dans leurs écoles. Elle décrit un modèle de capacité scientifique pour l’école, basé sur les conceptualisations existantes sur les capacités des écoles, et l’utilise comme cadre pour la présentation de quatre études de cas. Les constations tirées de l’analyse des rapports établis par les responsables enseignants et chefs d’établissement qui ont interprété leurs systèmes scolaires illustrent de quelle manière des éléments du cadre de la capacité scientifique des écoles interagissent pour soutenir, et parfois restreindre, les actions menées par les écoles pour améliorer l’enseignement des sciences. Cette étude discute des implications pour les établissements d’enseignement, les administrateurs et chercheurs catholiques qui essaient de donner la priorité aux sciences.
Capacidad científica de las escuelas: Estudio de cuatros escuelas católicas urbanas
Al trabajar desde la perspectiva de las escuelas como sistema y de la mejora escolar como un proyecto en transcurso (Hallinger & Heck, 2011; Jackson, 2000), el presente estudio investiga las perspectivas de docentes líderes y directores de cuatro escuelas católicas metropolitanas involucradas en esfuerzos para mejorar sus programas escolares de ciencias. Este estudio presenta y emplea un modelo de capacidad científica en las escuelas como marco para el desarrollo de cuatro estudios de casos. Los resultados obtenidos de la recopilación y del análisis de las interpretaciones de los informes de docentes líderes y directores de sus sistemas escolares ilustran cómo elementos del marco de capacidad científica de la escuela interactuaban para apoyar y a veces restringir los esfuerzos de mejora científica de las escuelas. Así mismo, el presente trabajo discute implicaciones para la educación en escuelas católicas, personal directivo e investigadores que intentan convertir las ciencias en una prioridad y construir una capacidad científica en las escuelas
A dimensional reduction approach based on the application of reduced basis methods in the context of hierarchical model reduction
In dieser Dissertation wird vor dem Anwendungshintergrund von Grundwasserströmungen eine neue Dimensionsreduktionsmethode hergeleitet, welche reduzierte Basistechniken zur Generierung von Basisfunktionen innerhalb der hierarchischen Modellreduktionsmethode anwendet. Dabei wird entlang der dominanten Fließrichtung des betrachteten Phänomens ein Standarddiskretisierungsverfahren eingesetzt und mit optimal an das Problem angepassten hierarchischen Basisfunktionen in transversaler Richtung kombiniert. Die hierarchischen Basen werden hierbei mit reduzierte Basistechniken aus Lösungen von in der Arbeit hergeleiteten parameterabhängigen niederdimensionalen Problemen ausgewählt. In einem zweiten Schritt wird die vorgeschlagene Dimensionsreduktionsmethode weiterentwickelt um auch nichtlineare Differentialgleichungen effizient behandeln zu können. In numerischen Experimenten für lineare und nichtlineare Differentialgleichungen wird die schnelle Konvergenz und Effizienz der Methode nachgewiesen. <br/
Partnering for Engineering Teacher Education
The aim of this article is to describe a specific approach to preparing elementary teacher candidates to teach engineering through a field-based undergraduate course that incorporates various engineering experiences. First, candidates visit a children’s museum to engage in engineering challenges and reflect on their experiences as learners as well as teachers. The majority of course sessions occur on-site in a neighborhood elementary school with a dedicated engineering lab space and teacher, where candidates help facilitate small group work to develop their own understandings about engineering and instructional practices specific to science and engineering. Candidates also have the option to attend the elementary school’s Family STEM Night which serves as another example of how informal engineering experiences can complement formal school-day experiences as well as how teachers and schools work with families to support children’s learning. Overall, candidates have shown increased confidence in engineering education as demonstrated by quantitative data collected through a survey instrument measuring teacher beliefs regarding teaching engineering self-efficacy. The survey data was complemented by qualitative data collected through candidates’ written reflections and interviews. This approach to introducing elementary teacher candidates to engineering highlights the value of a) capitalizing on partnerships, b) immersing candidates as learners in various educational settings with expert educators, c) providing opportunities to observe, enact, and analyze the enactment of high-leverage instructional practices, and d) incorporating opportunities for independent and collaborative reflection
Teaching, Learning and Leading with Schools and Communities: Preparing Sophisticated, Reflective, and Resilient Elementary STEM Educators
Loyola University Chicago’s Teaching, Learning and Leading with Schools and Communities (TLLSC) program is an ambitious break from traditional, university-based teacher preparation models. This clinically-based initial teacher preparation program, fully embedded in local schools and community organizations, takes an ecological perspective on the development of sophisticated, reflective, and resilient elementary science educators who are able to prepare and inspire students and act as agents of change in their schools. This paper describes how TLLSC leverages time for science across elementary teacher candidates’ entire program through an emphasis on practitioner inquiry and integrated (inter- and trans-disciplinary) teaching and learning. TLLSC’s innovative approach is designed to foster STEM habits of mind, integrate scientific practices, and support candidates’ ongoing self-examination of personal and social applications of science for themselves and their future students
Controlling Magnetism via Transition Metal Exchange in the Series of Intermetallics Eu(T1,T2)5In (T = Cu, Ag, Au)
Three series of intermetallic compounds Eu(T1,T2)5In (T = Cu, Ag, Au) have been investigated in full compositional ranges. Single crystals of all compounds have been obtained by self-flux and were analyzed by single X-ray diffraction revealing the representatives to fall into two structure types: CeCu6 (oP28, Pnma, a = 8.832(3)–9.121(2) Å, b = 5.306(2)–5.645(1) Å, c = 11.059(4)–11.437(3) Å, V = 518.3(3)–588.9(2) Å3) and YbMo2Al4 (tI14, I4/mmm, a = 5.417(3)–5.508(1) Å, c = 7.139(2)– 7.199(2) Å, V = 276.1(2)–285.8(1) Å3). The structural preference was found to depend on the cation/anion size ratio, while the positional preference within the CeCu6 type structure shows an apparent correlation with the anion size. Chemical compression, hence, a change in cell volume, which occurs upon anion substitution appears to be the main driving force for the change of magnetic ordering. While EuAg5In shows antiferromagnetic behavior at low temperatures, mixing Cu and Au within the same type of structure results in considerable changes in the magnetism. The Eu(Cu,Au)5In alloys with CeCu6 structure show complex magnetic behaviors and strong magnetic field-induced spin-reorientation transition with the critical field of the transition being dependent on Cu/Au ratio. The alloys adopting the YbMo2Al4 type structure are ferromagnets exhibiting unusually high magnetic moments. The heat capacity of EuAu2.66Cu2.34In reveals a double-peak structure evolving with the magnetic field. However, low-temperature X-ray powder diffraction does not show a structural transition
Human Galectins Induce Conversion of Dermal Fibroblasts into Myofibroblasts and Production of Extracellular Matrix: Potential Application in Tissue Engineering and Wound Repair
Members of the galectin family of endogenous lectins are potent adhesion/growth-regulatory effectors. Their multi-functionality opens possibilities for their use in bioapplications. We studied whether human galectins induce the conversion of human dermal fibroblasts into myofibroblasts (MFBs) and the production of a bioactive extracellular matrix scaffold is suitable for cell culture. Testing a panel of galectins of all three subgroups, including natural and engineered variants, we detected activity for the proto-type galectin-1 and galectin-7, the chimera-type galectin-3 and the tandem-repeat-type galectin-4. The activity of galectin-1 required the integrity of the carbohydrate recognition domain. It was independent of the presence of TGF-beta 1, but it yielded an additive effect. The resulting MFBs, relevant, for example, for tumor progression, generated a matrix scaffold rich in fibronectin and galectin-1 that supported keratinocyte culture without feeder cells. Of note, keratinocytes cultured on this substratum presented a stem-like cell phenotype with small size and keratin-19 expression. In vivo in rats, galectin-1 had a positive effect on skin wound closure 21 days after surgery. In conclusion, we describe the differential potential of certain human galectins to induce the conversion of dermal fibroblasts into MFBs and the generation of a bioactive cell culture substratum. Copyright (C) 2011 S. Karger AG, Base
Anomalous effects of Sc substitution and processing on magnetism and structure of (Gd1−xScx)5Ge4
The kinetic arrest observed in the parent Gd5Ge4 gradually vanishes when a small fraction (x = 0.025, 0.05 and 0.10) of Gd is replaced by Sc in (Gd1−xScx)5Ge4, and the magnetic ground state changes from antiferromagnetic (AFM) to ferromagnetic (FM). A first order phase transition coupled with the FM-AFM transition occurs at TC = 41 K for x = 0.05 and at TC = 53 K for x = 0.10 during heating in applied magnetic field of 1 kOe, and the thermal hysteresis is near 10 K. The first-order magnetic transition is coupled with the structural Sm5Ge4-type to Gd5Si4-type transformation. The magnetization measured as a function of applied magnetic field shows sharp metamagnetic-like behavior. At the same time, the AFM to paramagnetic transition in (Gd1−xScx)5Ge4 with x = 0.10, is uncharacteristically broad indicating development of strong short-range AFM correlations above the Néel temperature. Comparison of the magnetization data of bulk, powdered, and metal-varnish composite samples of (Gd0.95Sc0.05)5Ge4 shows that mechanical grinding and fabrication of a composite have little effect on the temperature of the first-order transformation, but short-range ordering and AFM/FM ratio below TC are surprisingly strongly affected
Termofizikalna i strukturalna studija IN 792-5A niklove superlegure
The presented paper deals with study of phase transformations temperatures of nickel based superalloy IN 792-5A with application of DTA – method and use of experimental laboratory system for simultaneous thermal analysis SETARAM Setsys 18TM. Samples taken from as-received state of superalloy were heated with controlled ramp rates (1, 5, 10 and 20 °C•min-1) and immediately after melting they were cooled with the same controlled ramp rate. The samples before and after DTA-analysis were also subjected to the phase analysis with use of scanning electron microscopy on the microprobe (JCXA 733) equipped with energy dispersive analyser EDAX (EDAM 3).Rad daje studiju temperature faznih transformacija niklove superslitine IN792-5A primjenom DTA metode te eksperimentalnog laboratorijskog sustava za simulaciju termalne analize SETARAM Setsys 18TM. Uzorci su uzeti iz početnog stanja legure i održavani definiranim brzinama (1, 5, 10 i 20 °C•min-1) i poslije ohlađeni kontroliranim brzinama. Uzorci su prije i poslije DTA analiza bili predmet fazne analize s primjenom skeninga elektronske mikroskopije (JCXA 733) dopunjeno s energi disperznom analizom EDAX (EDAM 3)
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