3,131 research outputs found

    Optical Characterization of Antimony-Based, Types-I and II, Multiple Quantum-Well Semiconductor Structures for Mid-Infrared Laser Applications

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    This experiment characterizes antimony-based, multiple quantum-well, types-I and -II, semiconductor samples designed for laser applications. The samples emit light in the 3-5-micron range to exploit an atmospheric transmission window, making them ideal for infrared (IR)-seeking missile countermeasures. Photoluminescence (PL) spectra were collected and yielded bandgap (E(sub g)) dependence-on-temperature relationships. The type-I sample was found to follow the Varshni equation, while the type-II samples showed a rise with temperature in a portion of the curve that should be linear according to the Varshni equation. The type-II samples followed the Varshni equation well at higher temperature. The PL study indicated that the type-I sample had better efficiency than the type-II samples, and that there is some change in efficiency with the waveguide nature of the sample. Carrier temperatures (T(sub c)) were derived from the PL study; all the samples for which Tc was derived operated in the optical phonon regime. The PL data were compared to the FEMB computer model and some correlation between the two in recombination energy was seen. A time-resolved photoluminescence (TRPL) experiment was conducted using the frequency upconversion technique. The experiment clearly found the upconverted signal, but there was a systematic error that prevented any further analysis of the data

    The use of altrenogest to control reproductive function in beef cattle

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    There has been great controversy involving progesterone (P4) levels during early pregnancy in cattle. The objectives of these experiments were to determine the effect of an early low dose administration of P4 or altrenogest (ALT) on pregnancy rates in repeat breeder (RPB) females, if an increase in pregnancy rates could result from a direct effect of P4 on the embryo and if ALT could support pregnancy in the absence of a functional CL. Firstly, ALT was evaluated for use as a progestin in cattle by synchronizing estrus in beef heifers. There were no differences in the number of females displaying behavioral estrus or in pregnancy rates when synchronized with ALT or MGA. A second experiment was designed to determine the effect of P4 or ALT supplementation during days 3 to 5 on pregnancy rate in RPB cattle. It was determined that 15 mg of P4 or ALT during days 3 to 5 increased pregnancy rates compared with nontreated breeding periods. A third experiment was designed to determine if P4 exerted a direct effect on the embryo. In vitro produced (IVP) embryos were cultured in the absence of a co-culture system. At day 3, post-insemination, embryos were cultured in the presence of P4 and evaluated on days 6 to 9. On day 7 post-insemination, there were significantly more grade 1 blastocysts from the P4 group compared with other treatment groups. Also, embryo developmental rates were increased when cultured in the presence of P4 and more of these embryos developed to the hatched blastocyst stage compared with other treatment groups. After a direct effect of P4 on developing IVP bovine embryos existed, it was determined that these embryos did not possess P4 receptors. Finally, it was demonstrated that ALT could support pregnancy in the absence of a functional CL. These experiments demonstrated that ALT could serve as a progestin in cattle and when administered in low doses during early pregnancy could improve pregnancy rates in RPB cows. These results are likely due to a direct effect of P4 on the embryo; however, this mechanism is by means other than binding the PR

    A community of learners in an elementary school recorder collegium

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    Thesis (D.M.A.)--Boston UniversityThe purpose of this study was to explore how students learned in an elementary school Collegium that consisted of SATB recorders. Using Rogoffs Theory of Community of Learners, an examination ofthe experiences of the students, the researcher, parents, classroom teachers, and the principal ofthe school occurred during one academic semester of instruction. The primary question that guided this study was: How did the students, instructor, teachers, and parents work together as a Community of Learners? The research questions for this study included: 1) What were the background conditions that led the students to audition for and take an active role in the Collegium ensemble?; How do the students engage with members ofthe community?; 3) How do the students engage in shared endeavors? Data collection included individual interviews, focus group interviews, journals, observations, and artifacts. Data was coded during the analysis process and revealed the following themes: Foundations ofthe Community uncovered influences from family members, as well as early pre-Collegium experiences; Entry points into the Collegium explored the initial interest by the participants, as they voiced their intentions to be a part ofthe ensemble and spoke oftheir attitudes regarding practice and learning processes; Experiences in the Collegium demonstrated perspectives on rehearsing together, self-preparedness, work attitudes, listening and concentration issues, group awareness, interdependence, learning together, and various issues ofmanaging the ensemble work with other academic commitments. Findings from this study indicated that close interactive behavior developed among the participants within the constructed environment, influenced by several factors, including foundational and educational backgrounds, exposure to the recorders, and an encouragement of a collaborative Community of Learners approach. The study concludes with a consideration ofthe author's role in the community, implications, and need for further study. Implications for the profession include establishing a learning environment that promotes collaborative learning, providing opportunities for students to engage with each other, and using the surrounding community of parents and teachers to assist with teaching students, which can lead to an improvement in the level of performance skills in an ensemble

    Identifying Domain Adjacent Instances for Semantic Parsers

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    When the semantics of a sentence are not representable in a semantic parser's output schema, parsing will inevitably fail. Detection of these instances is commonly treated as an out-of-domain classification problem. However, there is also a more subtle scenario in which the test data is drawn from the same domain. In addition to formalizing this problem of domain-adjacency, we present a comparison of various baselines that could be used to solve it. We also propose a new simple sentence representation that emphasizes words which are unexpected. This approach improves the performance of a downstream semantic parser run on in-domain and domain-adjacent instances.Comment: EMNLP 2018 Camera Read

    SOME ASPECTS OF PAYMENT BY NEGOTIABLE INSTRUMENT: A COMPARATIVE STUDY

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    The scenes are laid in London, New York, Berlin, and Paris. The plot begins with a debtor\u27s giving his creditor a negotiable instrument in payment of the debt. Complications are introduced when the creditor fails to perfect his rights on the instrument, and yet, naturally enough, wishes to collect his debt. Initially both debtor and creditor are satisfied when the negotiable instrument is given in payment. If it is a time instrument, the debtor has obtained an extension of credit. The creditor, on the other hand, has placed his claim in liquid form; he may realize upon it by discounting the instrument. The Anglo-American, German, and French legal systems, in their own way, attempt to safeguard both the interests of the debtor and the creditor

    Cypria petenensis, a new name for the Ostracod Cypria pelagica Brehm 1932

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    Recently during the preparation of a comprehensive account of the lake plankton (Hutchinson, in press) a rather unfortunate case of homonymy was discovered in the genus Cypria

    Purification of Bacillus subtilis aspartate transcarbamylase expressed in Escherichia coli (TB2/pLS2000)

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    Thesis (B.S.) in Biochemistry--University of Illinois at Urbana-Champaign, 1990.Includes bibliographical references (leaf 36)Microfiche of typescript. [Urbana, Ill.]: Photographic Services, University of Illinois, U of I Library, [1990]. 2 microfiches (43 frames): negative.s 1990 ilu n

    New developments in probing and targeting protein acylation in malaria, leishmaniasis and African sleeping sickness

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    Infections by protozoan parasites, such as Plasmodium falciparum or Leishmania donovani, have a significant health, social and economic impact and threaten billions of people living in tropical and sub-tropical regions of developing countries worldwide. The increasing range of parasite strains resistant to frontline therapeutics makes the identification of novel drug targets and the development of corresponding inhibitors vital. Post-translational modifications (PTMs) are important modulators of biology and inhibition of protein lipidation has emerged as a promising therapeutic strategy for treatment of parasitic diseases. In this review we summarize the latest insights into protein lipidation in protozoan parasites. We discuss how recent chemical proteomic approaches have delivered the first global overviews of protein lipidation in these organisms, contributing to our understanding of the role of this PTM in critical metabolic and cellular functions. Additionally, we highlight the development of new small molecule inhibitors to target parasite acyl transferases
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