Judul: Penentuan Bobot Kayu Apu Pistia stratiotes L sebagai Fitoremediator dalam Wadah Pendederan Ikan Gurami Oshpronemus goramy Lac.Ukuran 3 cm
Abstrak: The use of high stocking density in nursery causes a decrease of water quality. Technology that can be used to solve the low water quality in nursery of giant goramy was phytoremediation using Pistia stratiotes L. Purpose of this research was to determine the best weight ratio between Pistia stratiotes L and 33 liter water in nursery giant goramy size 3 cm. Giant goramy size 3 cm was maintained in an aquarium and was treated with different weight of Pistia stratiotes L consisted of 45 gram, 90 gram, 135 gram and controls (Pistia stratiotes L. 0 gram). Cleaning and water change was done once a week. This research showed that the treatment of Pistia startiotes L 45gram/33 liter water gave the best result in survival rate, absolute length of the growth, specific growth rate, feed efficiency and economically profitable.
Keyword: nursery, Osphronemus goramy Lac, water lettuce (Pistia stratiotes L.), phytoremediation

Judul: Pemanfaatan Ceratophyllum demersum L. sebagai Fitoremediator di Media Budidaya Ikan Gurame Osphronemus goramy Lac. dalam Wadah Terkontrol
Abstrak: Giant gourami Osphronemus goramy Lac. is one of the fish for food that has high economic value, but its production is not met with the market demand yet. The effort is needed to be done in order to increase production of giant gourami fry by the controlled vessel hatchery on phytoremediation system using water plant Ceratophyllum demersum L.. This study was analyzed determine the effect of C. demersum L. on water quality and survival rate. Fry was mean initial body length 1,69±0,15 cm with stock density 6 fish/l and were reared for 30 days in the aquarium 80x40x40 cm with provision of treatment C. demersum L. of 100 g, 200 g, and 300 g. Control was performed without the use of these plants. The results showed that the water quality (DO up to 8 mg/l; nitrate up to 0.1 mg/l), survival rate up to 97,39 %, and the mean body length was 1,34 times faster compared to mean initial body length on fry maintenance were affected by C. demersum L..
Keyword: Ceratophyllum demersum L, Osphronemus goramy Lac, phytoremediation

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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