Thesis (Ph. D.)--University of California, San Diego, 2001. / Vita. Includes bibliographical references (leaves 344-366).

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references (leaves 63-65). Also available on the Internet.

Thesis (M.S.)--Naval Postgraduate School, June 2003. / Title from title screen (viewed Feb. 11, 2004). Includes bibliographical references (p. 77-108). Also issued in paper format.

En debatt har förts under de senaste åren kring hur det kommer sig att Sveriges skolbarn visar brister i kunskaper i matematik i internationella tester som PISA och TIMSS. Forskning visar att förmågan att subtrahera är svårare för elever att erövra, jämfört med förmågan att addera. Detta är en intervjustudie som bygger på analys av 42 elevtest och nio påföljande intervjuer med elever i årskurs två. Studien undersöker vilka de kritiska aspekterna är då barn i årskurs två lär subtraktion med hjälp av skriftliga räknemetoder. Resultatet visar fyra kritiska aspekter som elever behöver urskilja för att lära subtraktion med skriftliga räknemetoder. Dessa kritiska aspekter är: att urskilja samband mellan siffror och mängder, att urskilja samband mellan operationella tecken och räknesätt, att urskilja att turordningen på talen påverkar summan samt att urskilja skillnaden mellan en bild som dekoration och som strategi för subtraktion. Didaktiska implikationer från studien är att lärare bör bedriva undervisning så att eleverna får möjlighet att urskilja de olika matematiska symbolerna som meningsbärare, relationen mellan talens ordning i den skrivna uppgiften och ordningen på hur talen ska dras ifrån varandra i subtraktionsräkning, att subtraktion är en matematisk aktivitet som är likadan varje gång samt att det är endast de ingående talen som varierar och slutligen hur bilden kan användas för att genomföra problemlösning.

Solar photovoltaic industry is a hot research field, massive attempts are going on all over the world to increase its productivity in different ways. One of the challenges for solar cells is the light spectrum mismatch losses, which referred to the part of solar spectrum that cannot be utilized to electricity by the conventional cells. Two ways have been suggested to overcome solar spectrum mismatch losses, the first is multi layered cells (tandem cells) with a different light behavior for each layer, and the second is spectrum conversion which is this researches subject. Spectral modification or conversion in solar cells industry has been studied and different lab scale models have been introduced. According to nanoscale journal, such technology may be the base of the next generation solar cells, mentioning specifically the use of luminescence down conversion and up conversion techniques to control the light spectrum on the solar cell, these endeavors targets to produce solar cells that is not subjugated to Shockley-Queisser maximum efficiency limit of 31%. This research aims to draw a map of various ideas introduced to incorporate similar technologies in solar cell products, beside further suggestion to enhance its technical behavior and to push the commercialization of the technology forward. This is expected to reveal clear image about technology’s future development map for the upcoming studies, and to create a motivation for further studies towards a commercial production scale. The proposed commercialized model will result in enhancing the maximum theoretical efficiency limit to 48% if all spectral mismatch loses have been eliminated. Quantum energy level diagrams have been illustrated to describe each model’s performance under a theoretical light spectrum.

B cells are capable of producing antibodies of diverse antigen specificities and effector functions to counter infection by a wide range of pathogens. The diversification of immunoglobulin (Ig) is achieved through a series of programmed DNA recombination and mutagenic events during B cell maturation. A key factor involved in the Ig diversification process is Activation Induced Cytidine Deaminase (AID). AID is a B cell specific enzyme that is critical for three distinct pathways of Ig diversification: class switch recombination, somatic hypermutation and Ig gene conversion. AID functions by deaminating cytosine to uracil in target DNA at the Ig loci. Although essential for effective immunity, the mutagenic activity of AID needs to be confined to the Ig loci in order to protect genomic integrity, but the underlying mechanism is not fully understood. In this study, I show that two lymphoid specific transcription factors, PU.1 and IRF4, play important roles in regulating AID function in chicken B cells. PU.1 and IRF4 have been implicated in many aspects of B cell development and function. The two factors could form a heterodimer and regulate target gene expression cooperatively. However, we found that PU.1 and IRF4 appear to have different impacts on AID function. We show that PU.1 is important for the expression of AID gene in chicken B cells, and the regulation appears to involve direct interaction of PU.1 with the AID gene. By comparison, IRF4 plays a minor role in AID expression. On the other hand, both PU.1 and IRF4 are required for efficient gene conversion that is mediated by AID at the Igλ locus. Moreover, the gene dosage of PU.1 is critical for AID function, since a severe gene conversion defect is observed in PU.1+/- cells. The function of PU.1 and IRF4 in AID-mediated gene conversion involves binding sites for the PU.1/IRF4 complex within a regulatory element at the Igλ locus. Future studies will be directed at understanding how PU.1 and IRF4 regulate AID-mediated gene conversion. / text

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

abstract / Chemistry / Doctoral / Doctor of Philosophy

No description available.