1,006 research outputs found
Fedora Goes to School: Experiences Creating a Curriculum Customization Service for K-12 Teachers
4th International Conference on Open RepositoriesThis presentation was part of the session : Fedora User Group PresentationsDate: 2009-05-20 01:30 PM â 03:00 PMEducational digital libraries provide a rich array of learning resources uniquely suited to support teachers to customize instruction. The problem we address is how to customize instruction to meet the learning needs of increasingly diverse student populations while ensuring that district learning goals and national and state standards are being met. This tension between supporting customization while supporting standards is further complicated by the challenges of scale: large urban school districts need technology infrastructure to support teachers district-wide to tailor curriculum, while still ensuring fidelity to learning goals. In partnership with Denver Public Schools (DPS), we are using open source digital library infrastructure available through the NSF-funded National Science Digital Library program to create a scalable Curriculum Customization Service. We are building on top of the Fedora-based NCore EduPak, which consists of the NSDL Collection System, the Digital Discovery System, and the NSDL Data Repository. DPS teachers will use this Service to (1) customize curriculum with digital library resources, formative assessments, and district-developed materials to aid student learning, (2) share their customizations as part of an online learning community and professional development program, and (3) discover, remix, and reuse other teachers' contributions. In this presentation, we will describe the Curriculum Customization Service and lessons learned from building an e-learning application supporting instructional planning and collaboration on top of Fedora. The Service uses learning goals as the central organizing concept of the interface. Organized around these are several curricular components including digital versions of the student textbook, digitized components of the associated teachers' guide (formative assessments, teaching tips, instructional resources, and background knowledge readings), and digital library resources. Digital library resources are further broken down by Top Picks (recommended), Images/Visuals, Animations, Additional Activities, and Working with Data. We will also present results from a 10 week pilot study with DPS middle and high school teachers (completed in Fall 2008) and plans for a large-scale, district-wide field study commencing in Fall 2009. In the pilot study, we used interviews, reflective essays, usage logs, and pop-up and email surveys to develop a detailed picture of how teachers were using the Service, and to examine how their usage of the Service changed over the course of the 10 week study. Results suggest the Service offers a powerful model for: (1) embedding digital library resources into mainstream teaching and learning practices and (2) enabling teachers to customize instruction to improve learner engagement and learning outcomes.NS
The Turnaround ERP Project: Strategies and Issues
A case study of an ERP project within a Fortune 100 company in the transportation industry is used to identify the strategies which facilitate a turnaround ERP project. The case study was developed using in-depth interviews with the President and the Chief Information Officer of the firm. The strategies described in this paper include project sponsorship, top management accountability, change control procedures, customization decision-making, measurement of project outcomes, management perception of the value of the ERP system, vendor relationship, and organizational change. To facilitate the turnaround project, top management involvement and accountability were critical. Modifications to the ERP system were minimized, and accountability mechanisms to monitor project outcomesâ both in time and costâ were established
Tensor Rank, Invariants, Inequalities, and Applications
Though algebraic geometry over is often used to describe the
closure of the tensors of a given size and complex rank, this variety includes
tensors of both smaller and larger rank. Here we focus on the tensors of rank over , which has as a dense subset the orbit
of a single tensor under a natural group action. We construct polynomial
invariants under this group action whose non-vanishing distinguishes this orbit
from points only in its closure. Together with an explicit subset of the
defining polynomials of the variety, this gives a semialgebraic description of
the tensors of rank and multilinear rank . The polynomials we
construct coincide with Cayley's hyperdeterminant in the case , and thus
generalize it. Though our construction is direct and explicit, we also recast
our functions in the language of representation theory for additional insights.
We give three applications in different directions: First, we develop basic
topological understanding of how the real tensors of complex rank and
multilinear rank form a collection of path-connected subsets, one of
which contains tensors of real rank . Second, we use the invariants to
develop a semialgebraic description of the set of probability distributions
that can arise from a simple stochastic model with a hidden variable, a model
that is important in phylogenetics and other fields. Third, we construct simple
examples of tensors of rank which lie in the closure of those of rank
.Comment: 31 pages, 1 figur
Numerical Modeling of Ooid Size and the Problem of Neoproterozoic Giant Ooids
Temporal variation in ooid size reflects important changes in physical and chemical characteristics of depositional environments. Two numerical models are used to evaluate the effects of several processes influencing ooid size. The first demonstrates that low supply of new ooid nuclei and high cortex growth rate each promote growth of large ooids. The second model demonstrates that high average water velocity and velocity gradient also enhance ooid growth.
Several Neoproterozoic oolites contain unusually large ooids, some reaching diameters of up to 16 mm. While lower nuclei supply and higher ooid growth rate may have prevailed prior to the evolution of carbonate-secreting organisms, neither difference can explain the presence of giant ooids in Neoproterozoic deposits because Archean through Mesoproterozoic ooids rarely exceed 5 mm in diameter. In the presence of lower nuclei supply and higher growth rate, high average water velocity may have allowed growth of such large ooids. Higher average water velocity could have been due to a prevalence of carbonate ramps over rimmed shelves during Neoproterozoic time
Writing to Transgress: Autobiographies and Family Trees as Multimodal and Culturally Sustaining Writing Pedagogy
Engaging today\u27s students in writing often requires more than formulas and prompts; it requires the use of culturally sustaining genres and modalities that speak to students\u27 lived experiences and what they know best. This paper chronicles an urban teacher\u27s attempt to create and use a writing prompt and a genre that would speak to and engage students who had previously experienced discouragement surrounding their academic writing. More specifically, we examine how the teacher used family trees, student-led interviews with family members, and family artifacts to engage his students in telling their own stories and, subsequently, how changes in this teacher\u27s views of effective writing brought with it enhanced teacher-student relationships
Which Triggers Produce the Most Erosive, Frequent, and Longest Runout Turbidity Currents on Deltas?
Subaerial rivers and turbidity currents are the two most voluminous sediment transport processes on our planet, and it is important to understand how they are linked offshore from river mouths. Previously, it was thought that slope failures or direct plunging of river floodwater (hyperpycnal flow) dominated the triggering of turbidity currents on delta fronts. Here we reanalyze the most detailed timeâlapse monitoring yet of a submerged delta; comprising 93 surveys of the Squamish Delta in British Columbia, Canada. We show that most turbidity currents are triggered by settling of sediment from dilute surface river plumes, rather than landslides or hyperpycnal flows. Turbidity currents triggered by settling plumes occur frequently, run out as far as landslideâtriggered events, and cause the greatest changes to delta and lobe morphology. For the first time, we show that settling from surface plumes can dominate the triggering of hazardous submarine flows and offshore sediment fluxes
FeH Absorption in the Near-Infrared Spectra of Late M and L Dwarfs
We present medium-resolution z-, J-, and H-band spectra of four late-type
dwarfs with spectral types ranging from M8 to L7.5. In an attempt to determine
the origin of numerous weak absorption features throughout their near-infrared
spectra, and motivated by the recent tentative identification of the E 4\Pi- A
^4\Pi system of FeH near 1.6 microns in umbral and cool star spectra, we have
compared the dwarf spectra to a laboratory FeH emission spectrum. We have
identified nearly 100 FeH absorption features in the z-, J-, and H-band spectra
of the dwarfs. In particular, we have identified 34 features which dominate the
appearance of the H-band spectra of the dwarfs and which appear in the
laboratory FeH spectrum. Finally, all of the features are either weaker or
absent in the spectrum of the L7.5 dwarf which is consistent with the weakening
of the known FeH bandheads in the spectra of the latest L dwarfs.Comment: accepted by Ap
Simulating novel gas turbine conditions for materials assessment: cascade design and operation
Integrated gasification combined cycles can incorporate pre-combustion carbon capture. High-H2 syngas produces high H2O levels after combustion, potentially accelerating gas turbine component damage. Determining materials systemsâ suitability for this novel environment requires exposures in representative environments. Thus, an existing 0.7â
MW burner rig was modified to generate the combustion environment and incorporate a cascade of 15 air-cooled turbine blades. Computational fluid dynamic calculations using blade dimensions and flow requirements supported the cascade design and determined blade placement within the gas flow. Trials of the modified unit have shown that a simulated combusted H2-rich syngas composition was generated at gas temperatures â€1440°C. A 1000â
h exposure has been carried out with thermal barrier coated blades to demonstrate the operation of the unit
The regulation of ion transport in the midgut of the lepidopteran larva Manduca sexta
Rapid growth during the larval stage of Lepidopteran insects is facilitated by vigorous transepithelial K+ transport from blood to gut lumen across the midgut. Active transport of K+ into the midgut lumen is required to energise amino acid uptake and is believed to contribute to the generation of the extremely high pH found in insect midgut. K+ transport is facilitated by a V-ATPase and K+/nH+ antiporter on the apical plasma membrane of the midgut goblet cell. A transmembrane voltage is generated by V-ATPase driven proton transport, consequently potassium is secreted by exchange for protons via the antiporter. This thesis confirms that the K+ transport system is abolished during periods of non feeding prior to pupation and during larval/larval moults. The moult from fourth to fifth instar was studied in detail. Transepithelial voltage, indicating net active K+ transport, was found to be approximately 100 mV during feeding periods but was found to fall to 0 mV during the moult. The transepithelial voltage was regenerated upon exit from the moult during ecdysis, just prior to resumption of feeding behaviour. The short circuit current was found to mirror these results. The pH of the midgut lumen was found to decline over the period of K+ transport inactivation. Thus during a moult, when the midgut is void of food, the K+ transport system is apparently not required and is consequently switched off. A transmembrane voltage is regenerated prior to the next gorge of food. The identity of the regulatory component of the K+ transport system was sought. The K+ pump is composed of two main components: the V-ATPase and the antiporter. ATPase activity assays on partially purified goblet cell apical membranes (GCAM) demonstrated that the V-ATPase was inactivated during the moult. ATP dependent proton transport into GCAM derived vesicles was also inactivated during the moult. ATP independent (antiporter) activity was not inhibited in vesicles derived from GCAM during the moult. The V-ATPase component thus appears to be the target of a control mechanism. In an effort to elucidate the mechanism of inactivation of the V-ATPase the V-ATPase structure was investigated using SDS gel electrophoresis. GCAM membranes, extracted from moulting or feeding larvae, were run on SDS gels and the V-ATPase subunit components were compared. Loss of V-ATPase activity paralleled the disappearance of specific V-ATPase subunits. The subunits missing were those considered to compose the peripheral V1 catalytic 'head' of the V-ATPase molecule. The integral membrane Vo subunits remained in the GCAM of moulting larvae. A mechanism, believed to be the first demonstration of which in vivo, of inactivation of a V-ATPase by dissociation of V1 from Vo is discussed. An attempt was made to reproduce the hormonal and intra cellular signals required for regulation of V-ATPase activity in vitro. cGMP was found to modestly activate transepithelial K+ transport. NADPH diaphorase staining suggested that nitric oxide synthase was present in the midgut tissue. However, sodium nitroprusside (a spontaneous generator of nitric oxide) did not stimulate K+ transport. This thesis has identified that K+ transport is regulated and that regulation occurs at the level of the V-ATPase. The V-ATPase is inactivated by the loss of the V1 domain of the molecule. Transport may be manipulated in vitro by various secondary messengers
Interaction of hot corrosion fatigue and load dwell periods on a nickel-base single crystal superalloy
The effects of type II hot corrosion on the fatigue resistance of turbine blade superalloys is of growing interest as gas turbine (GT) original equipment manufacturers (OEMs) strive to optimise the operational efficiencies and versatilities of GT systems. Hot corrosion fatigue has been observed in the under platform regions of first stage GT blades, this location is subject to both relatively high principal stresses and stress gradients, combined with temperatures up to those associated with type II hot corrosion (500â700âŻÂ°C). The effect of the deposition flux of corrosive salt species and the tensile stress dwell period on the fatigue performance and resultant crack morphologies of single crystal (SC) superalloy CMSX-4 has been studied at 550âŻÂ°C. Deposit recoat methodologies were applied to specimens that were cyclically fatigued with a load-controlled trapezoidal waveform. It was observed that introducing a longer dwell period increased the number of {1âŻ0âŻ0} crack initiations and reduced the fatigue life (load cycles to failure). Optical and SEM microscopy and EDX techniques were used to examine specimen fractography, and mechanisms of crack advance and propagation discussed
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