Judul: Studi Komparatif Pembobotan Kata untuk Temu Kembali Informasi Dokumen Bahasa Indonesia
Abstrak: One of the classical models of Information Retrieval (IR) systems is the vector space model. Vector in this model represents the weight of terms contained in the documents and queries. A term can be a word, a phrase, or a unit in a document describing the context of the document. Since each term has a different level of importance in the document, weighting is needed. The commonly used weighting method is TF-IDF (Term Frequency Inverse Document Frequency). Previous research indicates that the distribution of term weighting follow the Poisson distribution, hence a method called RIDF (Residual Inverse Document Frequency) was developed. Other weighting methods by considering the query is called Query Term weighting. Both of the latter methods has not been implemented for documents in Indonesian. This research implements the methods TF-IDF, RIDF and Query Term Weighting on search engine for documents in Indonesian. The result of this research is a search engine with an average precision of 63,9%.
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Judul: RDF Retrieval untuk Dokumen Bahasa Indonesia dengan Pembobotan Per Konteks
Abstrak: Penelitian temu kembali informasi pada dokumen RDF sudah dilakukan. Akan tetapi, penelitian tersebut belum memperhatikan struktur dari dokumen RDF. Penelitian ini mengembangkan sistem temu kembali informasi pada dokumen RDF dengan memperhatikan struktur dokumen yaitu dengan membedakan bobot pada setiap konteks (tag) yang ada pada dokumen RDF. Pembobotan yang digunakan adalah tf-idf. Bobot yang dihasilkan pada setiap konteks dikalikan dengan suatu koefisien dengan nilai 0.2, 0.4, 0.6, 0.8, atau 1.0. Sistem temu kembali informasi yang dibangun dievaluasi dengan menggunakan 29 kueri. Penelitian ini menghasilkan nilai average precision (AVP) sebesar 0.89721. Nilai tersebut lebih tinggi 1.91% jika dibandingkan dengan sistem temu kembali informasi yang tidak membedakan bobot per konteks.
Keyword: Information retrieval, RDF, Pembobotan konteks, Dokumen RDF, Penyimpanan dokumen pada sesame, Proses indexing, Pencarian dokumen, Informasi dokumen

Judul: Growth, Concentration Chlorophyll-a, and Structure of Macroalgae Gracilaria edulis in the Culture Media Containing Copper
Abstrak: The physiological responses (specific growth rate, concentration of chlorophyll-a, morphological and anatomical structure of the vegetative cells) of the marine macroalga Gracilaria edulis at the different concentrations of copper (0.01 as control, 0.04, 0.06 and 0,5 ppm) delivered continuously for 28 days under controlled laboratory conditions were investigated. Result showed that the degree of copper toxicity depends on both factor the concentration and exposure time. Copper concentration and day of exposure decreased significantly the specific growth rate (SGR) of the Gracilaria edulis but only 0,5 ppm Cu decreased the chlorophyll-a content when compared to control. Of the various physiological end points measured, growth proved to be the most sensitive response than chlorophyll-a with reductions in specific growth rate (SGR). The reason for this could be related to a greater sensitivity of the enzymes involved in growth than those related to chlorophyll-a or a greater energy needs to maintain cellular integrity and metabolic processes under sublethal Cu stress. In all cases, the main effect on vegetative cells were structure changes in cortex and subcortex cells, compared to control, macroalgae exposed to copper showed depigmentation and blending in the lateral branches, heavy staining of the cell wall and severe damage of cell membrane, while the mucilage and the cell walls was densely fibrillar, thick and heavily stained, the cortex cell was clearly vacuolated, the presence of endophytic on the cell wall and endophytic spores in the mucilage. The presence vacuoles should be related to a metal immobilization mechanism, minimizing the Cu toxicity for cells. The epiphytic bacteria can act as a biofilter diminishing the availability of Cu for macroalgae accumulation.
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