<p> In six conditioned suppression experiments with rats, two conditioned stimuli (CSs) were individually trained and then tested as a compound. In one set of experiments, the suppressing effect of the compound was greater than that of either CS presented alone. This result is referred to as compound summation. In a second set of experiments, the suppressing effect of the compound was less than that of the "stronger" suppressing individual CS. This result is referred to as compound attenuation. The combination of summation and attenuation makes it possible to determine whether CSs with unknown properties are weakly excitatory (i.e., weak suppressors) or inhibitory (i.e., conditioned characteristics that are opposite the excitatory suppressing effect). If an unknown CS is tested in compound with a second CS known to be excitatory, summation indicates that the unknown stimulus is excitatory, while attenuation indicates that the unknown stimulus is inhibitory. In a final set of experiments, this compound test procedure was used to examine extinction and differential conditioning as inhibitory training procedures. Extensive extinction of a previously trained CS, even far beyond the point at which suppression vanished, was found to be an ineffective inhibitory training procedure. Rather, compound tests showed that the stimulus retained excitatory properties. Differential conditioning was found to be a very effective inhibitory training procedure, regardless of whether presentations of a previously trained CS and shock, shook alone, or the previously trained CS - alone accompanied the unreinforced CS undergoing inhibitory conditioning. These findings are discussed in terms of current theories of conditioning and unresolved issues surrounding the acquisition and maintenance of inhibitory properties.</p> / Thesis / Doctor of Philosophy (PhD)

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京都大学 / 新制・課程博士 / 博士(理学) / 甲第23718号 / 理博第4808号 / 新制||理||1688(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 時任 宣博, 教授 依光 英樹, 教授 若宮 淳志 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

The purpose of this master thesis is to make use of the category taxonomy of Wikipedia to determine the most reasonable split from the suggestions generated by an independent compound word splitter. The articles a word was found in can be seen as a group of contexts the word can occur in and also different representations of the word, i.e. an article is a representation of the word. Instead of only analysing the data of each single article, the intention is to find more data for each representation/context to perform an analysis on. The idea is to expand each article representing one context by including related articles in the same category. Two perceptions of a ”reasonable split” was studied. The first case was a split consisting of only two parts and the second case of unlimited parts. This approach is well-suited for choosing the correct split out of a several suggestions but unsuitable for identifying compound words. It would more often than not decide to not split a compound word. It is very dependant on the compound words appearing in Wikipedia. / Syftet med detta examensarbete är att utse den rimligaste uppdelningen av ett sammansatt ord genom användning av Wikipedias kategoritaxonomi. Förslag på olika uppdelningar genereras av en oberoende färdig algoritm. Artiklarna som ett ord finns can ses som en grupp av kontexter som ett ord kan förekomma i och olika framställningar av ett ord. Avsikten är att hitta mer data för varje framställning/kontext att utföra en analys på istället för att bara analysera artikeln ordet hittades i. Idéen som ska testas är att expandera varje artikel som representerar en kontext genom att inkludera relaterade artiklar i samma kategori. Två olika synsätt på ”rimliga uppdelningar” studerades. Första fallet var att endast dela upp sammansatta ord i två delar och andra fallet var att dela upp i obestämt antal delar. Metoden visade sig utmärka sig på att välja rätt uppdelning när den väl gjorde ett försök. En stor nackdel var att den ofta valde att inte dela upp sammansättningar trots att den skulle ha gjort det. Metoden är mycket beroende av att sammansättningarna måste finnas i Wikipedia.

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No / Cajanus cajan L, a member of the family Fabaceae, was identified from the Nigerian antimalarial ethnobotany as possessing antimalarial properties. The bioassay-guided fractionation of the crude methanol extract of C. cajan leaves was done in vitro using the multiresistant strain of Plasmodium falciparum (K1) in the parasite lactate dehydrogenase assay. Isolation of compound was achieved by a combination of chromatographic techniques, while the structure of the compound was elucidated by spectroscopy. This led to the identification of a cajachalcone, 2′,6′-dihydroxy-4-methoxy chalcone, as the biologically active constituent from the ethyl acetate fraction. Cajachalcone had an IC50 value of 2.0 μg/mL (7.4 μM) and could be a lead for anti-malarial drug discovery.

published_or_final_version / abstract / Physics / Doctoral / Doctor of Philosophy