293 research outputs found

    Conceptual Data Modeling in the Introductory Database Course: Is it Time for UML?

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    Traditionally, the typical undergraduate database course uses a form of Entity-Relationship (ER) notation when teaching conceptual modeling. While we have seen an increase in the academic coverage of UML in the database course, it is very rare to see UML as the primary modeling notation when teaching conceptual data modeling. However, outside of academe, there has been advocacy for the use of UML as an effective modeling tool for database design and for it to provide a unifying modeling framework. This paper examines the level of support for using UML vs. established ER notations for teaching conceptual data modeling in the introductory undergraduate database course. An analysis of textbook and tool support as well as a survey of what IS undergraduate programs are using in their introductory undergraduate database courses is included

    Emotional Responses to Computer-Based Training Materials in Education

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    This paper discusses the results of an experiment that examines how emotional responses influence student satisfaction ratings with computer-based training materials. A comparison between tutorial-based and a simulation-based training showed significant differences in student emotional responses, satisfaction and continuance. The authors caution educators to consider the benefits and limitations of more automated assessment and learning simulation tools versus traditional application-embedded tutorials, as additional layers of training automation may lower student ease-of-use and satisfaction ratings, and ultimately, their interest in the subject

    THE ALIGNED RANK TRANSFORM PROCEDURE

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    Recent work has shown that the rank transform methodology is flawed when applied to multifactor designs with interactions. A simple fix-up is proposed and shown to apply to designs typical of those found in agricultural research including split-plots. Simulation results suggest that the fix-up provides a valid procedure for analyzing multifactor designs when error distributions are symmetric or moderately skewed. The procedure appears to have power advantages over normal theory ANOVA when error distributions are heavy tailed

    After Testimony: The Ethics and Aesthetics of Holocaust Narrative for the Future

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    Imre Kertész's fatelessness : fiction as testimony / J. Hillis Miller -- Challenges for the successor generations of German-Jewish authors in Germany / Beatrice Sandberg -- Recent literature confronting the past : France and beyond / Philippe Mesnard, translated by Terence Cave -- Performing a perpetrator as witness : Jonathan Littell's Les bienveillantes / Susan Rubin Suleiman -- The ethics and aesthetics of backward narration in Martin Amis's Time's arrow / James Phelan -- The face-to-face encounter in Holocaust narrative / Jeremy Hawthorn -- Knowing little, adding nothing : the ethics and aesthetics of remembering in Espen Søbye's Kathe, always lived in Norway / Anniken Greve -- "When facts are scarce" : authenticating strategies in writing by children of survivors / Irene Kacandes -- Objects of return / Marianne Hirsch -- Narrative, memory, and visual image : W.G. Sebald's Luftkrieg und Literatur and Austerlitz / Jakob Lothe -- Which narrative of Auschwitz? A narrative analysis of Laurence Rees's documentary Auschwitz : the Nazis and "the final solution" / Anette H. Storeide -- Moving testimonies : "unhomed geography" and the Holocaust documentary of return / Janet Walker -- From Auschwitz to the Temple Mount : binding and unbinding the Israeli narrative / Sidra DeKoven Ezrahi -- The melancholy generation : Grossman's Book of interior grammar / Daphna Erdinast-Vulcan -- Fractured relations : the multidirectional Holocaust memory of Caryl Phillips / Michael Rothberg -- Hiroshima and the Holocaust : tales of war and defeat in Japan and Germany-a contrastive perspective / Anne ThelleItem embargoed for five year

    Energetic proton spectra in the 11 June 1991 solar flare

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    We have studied a subset of the 11 June 1991 solar flare γ-ray data that we believe arise from soft proton or ion spectra. Using data from the COMPTEL instrument on the Compton Observatory we discuss the gamma-ray intensities at 2.223 MeV, 4–7 MeV, and 8–30 MeV in terms of the parent proton spectrum responsible for the emission

    Extended γ‐ray emission in solar flares

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    During the solar flare events on 11 and 15 June 1991, COMPTEL measured extended emission in the neutron capture line for about 5 hours after the impulsive phase. The time profiles can be described by a double exponential decay with decay constants on the order of 10 min for the fast and 200 min for the slow component. Within the statistical uncertainty both flares show the same long‐term behaviour. The spectrum during the extended phase is significantly harder than during the impulsive phase and pions are not produced in significant numbers before the beginning of the extended emission. Our results with the measurements of others allow us to rule out long‐term trapping of particles in non‐turbulent loops to explain the extended emission of these two flares and our data favour models based on continued acceleration

    Effect of extraction variables on total phenol yield in some selected legumes indigenous to Nigeria

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    There are increasing research efforts on the possibilities of the utilization of natural sources of bioactive compounds for the dietary management of certain degenerative diseases due to their deleterious health effects associated with the the use of synthetic chemicals. Therefore, this study evaluated the yield of total phenol from bambaranut, cowpea, red bean and pigeon pea. A set of single factor experiments, namely solvent types (acetone, ethanol and methanol), solvent concentration (20 – 100 %, v/v), extraction time (30 – 50 min) and extraction temperature (40 – 60 C), were evaluated for the optimization of total phenol recovery. The results show that extraction variables significantly (p < 0.05) affected the total phenol yield. Ethanol at 60% concentration (v/v) incubated at 50 C for 40 min gave the highest total phenol (217.11 mg/100 g) yield in bambaranut. In cowpea, ethanol at 90% concentration (v/v) incubated at 50 C for 50 min gave the highest total phenol (192.61 mg/100 g). Methanol at 100% concentration incubated at 50 C for 40 min gave the highest total phenol (212.00 mg/100 g) in the red bean while methanol at 100 % concentration (v/v) incubated at 50 C for 40 min gave the highest total phenol (196.33 mg/100 g) in pigeon pea

    Energetic proton spectra in the 11 June 1991 solar flare

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    The June 11, 1991 gamma-ray flare seen by the Compton Gamma-ray Observatory (CGRO) displays several features that make it a dynamic and rich event. It is a member of a class of long duration gamma-ray events with both 2.223 MeV and greater than 8 MeV emission for hours after the impulsive phase. It also contains an inter-phase between the impulsive and extended phases that presents a challenge to the standard gamma-ray line (GRL) flare picture. This phase has strong 2.223 MeV emission and relatively weak 4.44 MeV emission indicative of a very hard parent proton spectrum. However, this would indicate emission greater than 8 MeV, which is absent from this period. We present the application of new spectroscopy techniques to this phase of the flare in order to present a reasonable explanation for this seemly inconsistent picture

    Gamma ray measurements of the 1991 November 15 solar flare

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    The 1991 November 15 X1.5 flare was a well observed solar event. Comprehensive data from ground-based observatories and spacecraft provide the basis for a contextual interpretation of gamma-ray spectra from the Compton Gamma Ray Observatory (CGRO). In particular, spectral, spatial, and temporal data at several energies are necessary to understand the particle dynamics and the acceleration mechanism(s) within this flare. X-ray images, radio, Ca XIX data and magnetograms provide morphological information on the acceleration region [4,5], while gamma-ray spectral data provide information on the parent ion spectrum. Furthermore, time profiles in hard X-rays and gamma-rays provide valuable information on temporal characteristics of the energetic particles. We report the results of our analysis of the evolution of this flare as a function of energy (∼25 keV–2.5 MeV) and time. These results, together with other high energy data (e.g. from experiments on Yohkoh, Ulysses, and PVO) may assist in identifying and understanding the acceleration mechanism(s) taking place in this event

    X- and gamma-ray observations of the 15 November 1991 Solar Flare

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    This work expands the current understanding of the 15 November 1991 Solar Flare. The flare was a well observed event in radio to gamma-rays and is the first flare to be extensively studied with the benefit of detailed soft and hard X-ray images. In this work, we add data from all four instruments on the Compton Gamma Ray Observatory. Using these data we determined that the accelerated electron spectrum above 170 keV is best fit with a power law with a spectral index of −4.6, while the accelerated proton spectrum above 0.6 MeV is fit with a power law of spectral index −4.5. From this we computed lower limits for the energy content of these particles of∼1023 ergs (electrons) and ∼1027 ergs (ions above 0.6 MeV). These particles do not have enough energy to produce the white-light emission observed from this event. We computed a time constant of 26+20−15 s for the 2.223 MeV neutron capture line, which is consistent at the 2σ level with the lowest values of ∼70 s found for other flares. The mechanism for this short capture time may be better understood after analyses of high energy EGRET data that show potential evidence for pion emission near ∼100 MeV
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