Judul: Profil Asam Lemak dan Asam Amino Gonad Bulu Babi
Abstrak: Sea urchins are one of the biological resources with a high level of species diversity in Indonesia. Most people assume that these sea urchins are harmful animals because they contain poisonous compound and can damage of coral reef communities. Purpose of this research was to determine the chemical composition, fatty acids and amino acids profiles of sea urchins gonads Diadema setosum, Echinothrix calamaris and Echinothrix diadema. The chemical composition, fatty acids and amino acids profile were analyzed using AOAC method. D. setosum gonads contained 60.37% total fatty acids with 29 kinds of fatty acids (11 SAFA, 8 MUFA, 10 PUFA). E. calamaris and E. diadema gonads contained 58.35% and 58.55% total fatty acids with 30 kinds of fatty acids (11 SAFA, 9 MUFA, 10 PUFA). The highest content of fatty acid is palmitic acid (16.55-18.44%). Sea urchins gonads contained unsaturated fatty acids omega-3 (3.16-3.99%), omega-6 (9.21-13.88%), omega-9 (3.95-5.01%), and EPA (2.3-2.89%). Sea urchins gonads contained 15 kinds of amino acids, they are 8 kinds of essential amino acid and 7 kinds of non essential animo acid. D. setosum, E.calamaris and E.diadema gonads contained 13.41%, 10.49% and 10.71% total amino acid.
Keyword: proximate., sea urchins gonads, fatty acids, amino acids

Judul: Performance of gonad development of sea urchin (Tripneustes gratilla) fed artificial diet with different protein level and energy-protein ratio, and estradiol 17-β hormone.
Abstrak: Sea urchin is one of the important marine biota which has economic value. Its gonads fetch high price in many countries. The research was conducted in four phases. The first phase was to study the biological reproduction aspect of sea urchin (Tripneustes gratilla) that catched from Kupang Bay. Ten to thirty individuals were catched every month from May until December 2008. Parameters observed consisted of gonad weight, gonad somatic index, oocyte diameter, gonad colour, test diameter, and body weigth. The second phase was to study gonad development of sea urchin that reared in captivity. Twenty five individuals were reared in tank (2.5 x 2.0 x 1.5 m) and fed macroalga every two days. Parameters such as testosterone and estradiol hormone in gonad and coelomic fluids, gonad weight, and oocyte diameter were measured every two weeks. The third phase was to know the requirement of protein and energy-protein ratio to maximize gonad production and quality. Adult sea urchins were collected from the wild and held in aquarium at laboratory. Nine formulated diet were prepared in order to examine two experimental factors: (1 protein levels (22, 27, and 32%) and (2) energy protein ratio (9, 11, 13 kcalGE/g protein). Gonad weight, protein, total carotenoid, β-carotene, colour, texture, and gonad taste were evaluated at the end of the experiment. The fourth phase was to study the effect of estradiol-17β at dose of 10 and 30 μg/g wet weight of diet for accelerating gonad maturation of sea urchin at different test diameter: 50 – 59, 60 – 69, and 70 – 79 mm. Parameter observed in this experiment were the same as that of the second phase. Result from the first phase showed gonad of sea urchin consisted of five stages of development, namely; developing/recovering, growing, pre mature, mature, and partial spawning. At the second phase, development stages of gonad were the same as observed at the first phase, gonad maturation achieved maximum at 9th week. At the third phase, the 32% protein level and 9 kcal GE/g energy-protein ratio gave higher production and gonad quality. At the fourth phase, estradiol-17β at dose 30 μg could accelerate gonad maturation of sea urchin at the 60 – 69 mm test diameter. Gonad maturation achieved maximum at 7th week. As conclusion, application of 32% protein and 9 ccal GE/g energy-protein ratio, as well as estradiol-17β could maximize gonad performance.
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Judul: Bifurkasi Hopf pada Model Siklus Bisnis Kaldor Kalecki tanpa dan dengan Waktu Tunda
Abstrak: Business cycle model is one of dynamical system models in economic. One of the business cycles model is Kaldor-Kalecki model. Kaldor-Kalecki business cycle model that is written in delayed defferential equations, is a business cycle model that involves gross product and capital stock of a company. In this paper Kaldor-Kalecki business cycle model is analyzed using both nondelay and delay in time of capital stock. By Taylor expansion for the time delayed model, an analysis of stability around the fixed points has been done. Furthermore, by using Hopf bifurcation theorem, it can be shown that there exists periodic orbits and limit cycle. In the nondelayed model, changing the parameter of goods market could lead to the occurrence of Hopf bifurcation and the existence of limit cycle. Similarly, for the delayed model, it has been shown that changing the time delay parameter may result in the occurrence of Hopf bifurcation and limit cycle.
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