2 resultados para Demand scenarios

em Brock University, Canada


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The purpose of the study,was to investigate the ways in which secondary school principals make decisions that have an ethical dimension, and the reasons they use to justify their choices. The ethical principles and concepts, as well as the scenarios, were adapted from The Ethics ofSchool Administration by Strike, Haller, and Soltis (1998). In this study, 32 secondary principals from a school board in Ontario were asked to complete a descriptive survey which was designed to have principals make administrative decisions in response to 5 hypothetical scenarios. The open-ended questions were expected to elicit responses that were reflective of the principals' actual decision-making strategies. The survey also required them to justify and explain their reasons for each decision. The data were analyzed and 4 major categories ofjustifications emerged: pedagogy, legalism, moral code, and democracy. The results indicate that the decisions made by principals are grounded in various perspectives. While the data did not indicate any explicit knowledge of ethical principles and concepts, the principals' responses suggest sound and valid reasoning for their decision making, addressing the principles and concepts from a variety of viewpoints and using diverse justifications.

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(A) Most azobenzene-based photoswitches require UV light for photoisomerization, which limit their applications in biological systems due to possible photodamage. Cyclic azobenzene derivatives, on the other hand, can undergo cis-trans isomerization when exposed to visible light. A shortened synthetic scheme was developed for the preparation of a building block containing cyclic azobenzene and D-threoninol (cAB-Thr). trans-Cyclic azobenzene was found to thermally isomerize back to the cis-form in a temperature-dependent manner. cAB-Thr was transformed into the corresponding phosphoramidite and subsequently incorporated into oligonucleotides by solid phase synthesis. Melting temperature measurement suggested that incorporation of cis-cAB into oligonucleotides destabilizes DNA duplexes, these findings corroborate with circular dichroism measurement. Finally, Fluorescent Energy Resonance Transfer experiments indicated that trans-cAB can be accommodated in DNA duplexes. (B) Inverse Electron Demand Diels-Alder reactions (IEDDA) between trans-olefins and tetrazines provide a powerful alternative to existing ligation chemistries due to its fast reaction rate, bioorthogonality and mutual orthogonality with other click reactions. In this project, an attempt was pursued to synthesize trans-cyclooctene building blocks for oligonucleotide labeling by reacting with BODIPY-tetrazine. Rel-(1R-4E-pR)-cyclooct-4-enol and rel-(1R,8S,9S,4E)-Bicyclo[6.1.0]non-4-ene-9-ylmethanol were synthesized and then transformed into the corresponding propargyl ether. Subsequent Sonogashira reactions between these propargylated compounds with DMT-protected 5-iododeoxyuridine failed to give the desired products. Finally a methodology was pursued for the synthesis of BODIPY-tetrazine conjugates that will be used in future IEDDA reactions with trans-cyclooctene modified oligonucleotides.