Judul: Latent Semantic Indexing PadaSistem Temu Kembali Dokumen Bahasa Indonesia
Abstrak: Pengindeksan semantik laten merupakan salah satu metode yang berhasil diterapkan pada sistem temu kembali informasi dengan menggunakan dokumen berbahasa Indonesia. Metode yang digunakan adalah dengan memanfaatkan struktur tingkat tinggi implisit dalam asosiasi istilah dengan dokumen (struktur semantik) untuk meningkatkan deteksi dokumen relevan berdasarkan istilah yang ditemukan dalam kueri dalam bahasa Indonesia. Mesin yang dievaluasi menggunakan dokumen pertanian dan dokumen tanaman obat kemudian dibandingkan hasil penyimpanan matriks yang dihasilkan menggunakan Singular Value Decomposition (SVD) dan Semi Discrete Decomposition (SDD). Kemudian nilai k optimum akan ditentukan setelah diperoleh nilai relevan tertinggi pada nilai k tersebut.
Keyword: Information Retrieval, Singular Value Decomposition (SVD), Semi Discrete Decomposition (SDD)

Judul: Mesin Pencari Dokumen Bahasa Indonesia Menggunakan Latent Semantic Indexing dengan Pembobotan Global
Abstrak: Current users tend to like search engine based on semantic of word. This is caused by the existence of synonymy and polysemy problems in the selection of the use of the word. One technique to resolve these issue is Latent Semantic Indexing (LSI). LSI has the ability to find relevant documents even if the word of the query are not written in the document. Currently, TF-IDF term weight algorithm is widely applied in search engines. Xia and Chai (2011) stated that, in a document collection, the term with higher frequency and hypo-dispersion distribution usually contains less information. The purpose of this research is to implement LSI using Singular Value Decomposition (SVD) method with term distribution based global term weight. This research used 1000 Indonesian agricultural documents. The performance of search engine using LSI with term-distribution-based global term weight gave highest average precision around 40.47%. The test result also showed that LSI with term-distribution-based global term weight gives better acuracy than LSI with TF-IDF.
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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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