Judul: Seleksi Spermatozoa Domba Garut dengan Metode Sentrifugasi Gradien Densitas Percoll
Abstrak: Good quality of sperm was necessary prepared in order to increase the efficacy of in vitro fertilization. The good quality of sperm could be obtained through selection using percoll density gradient centrifugation method. The aim of this research was to determine an optimal combination of speed and centrifugation time in providing better quality of sperm with the lowest mortality rate or damage. Garut sheep fresh semen with 200 million cells/ml in concentration was used as research sample for each treatments. Factorial completely randomized design was used as research design, with one control and sixteen treatments combination of centrifugation speed and time: (1) 200 xg for 5 min; (2) 200 xg for 10 min; (3) 200 xg for 15 min; (4) 200 xg for 20 min; (5) 300 xg for 5 min; (6) 300 xg for 10 min; (7) 300 xg for 15 min; (8) 300 xg for 20 min; (9) 400 xg for 5 min; (10) 400 xg for 10 min; (11) 400 xg for 15 min; (12) 400 xg for 20 min; (13) 500 xg for 5 min; (14) 500 xg for 10 min; (15) 500 xg for 15 min; and (16) 500 xg for 20 min. All of control and treatments combination were replicated for three times. The sperms variables were observed sperm concentration, percentage of live sperms, percentage of progressive motility sperms and percentage of normal sperms. Data were evaluated by two way analysis of variance (ANOVA), and differences between treatment group were determined by a post hoc, Duncan’s multiple range test (DMRT). Differences were considered significantly at a probability value (P) of 0.05. The results showed that the treatment of centrifugation 400 xg for 15 min gave the optimal combination significantly (P<0.05) with the highest sperms concentration (33.33%), the highest percentage of living sperms (74.82%), the highest percentage of progressive motility sperms (57.56%), and the highest percentage of normal sperms (86%) were obtained. It is concluded that sperms selection using percoll density gradient centrifugation method is able to increase the percentage of sperms concentration, percentage of live sperms, percentage of progressive motility sperms, and percentage of normal sperms. Centrifugation should be done at the speed of 400 xg for 15 min to decrease the damage rate of sperms.
Keyword: 

Judul: Kualitas Spermatozoa Cauda Epididimis Domba Garut yang diberi Pakan Limbah Tauge dan Indigofera sp pada Pengencer Tris Kuning Telur
Abstrak: Feed is one of the important factor to improve the quality of spermatozoa. Feed can be made from waste bean sprout and legume Indigofera sp. Garut ram has high economic value, but it is faced with the problem of limited number of a good quality of male. One of method that can be used to solve a problem is the utilization of cauda epididymal sperm since it has motility and an able to fertilize oocytes as well as ejaculated sperm. The purpose of this research was to determine the effect of feeding (waste bean sprout and Indigofera sp) to increase the quality of garut ram sperm. This research used 8 garut male with age around 11 months and had been raised for 3 months. They were divided into two groups, the first group was fed with 30% waste bean sprout and the second group was fed with 30% Indigofera sp. Parameter of semen quality was analyzed as follow: for the volume, color and consistency were expressed by descriptively, while testis weight, sperm concentration and cytoplasmic droplet were tested by T-test and followed by regression test for correlation between testis weight and sperm concentration. Sperm motility, sperm viability, integrity of sperm plasma membrane and secondary abnormality were analyzed using Completely Randomized Design, Faktorial (2x4) with four replication. The first factor was type ration (waste bean sprout and Indigofera sp) and the second factor was storage time (day 0, 1st, 2nd, 3th). Data was analyzed by analysis of variance and continued with Duncan test to observed the different between treatments. Results of the experiment showed that volume, color and consistency of semen were same in all treatments, while testis weight, sperm concentration and cytoplasmic droplet were not significant different in type ration treatments by T-test (P>0.05). There were no correlation between testis weight and sperm concentration (P>0.05) and expressed as Y = 5654.26 - 3.96X ; R2 = 0.003. Furthermore sperm viability were significant different in all treatments by analyzed of variance (P<0.05). The integrity of sperm plasma membrane and sperm motility were significant different in storage time treatment (P<0.05), but were not significant different in type ration by analyzed of variance (P>0.05). It can be summarized that both of 30% waste bean sprout and 30% Indigofera sp feed treatments were not significantly influence on all of parameter sperm quality.
Keyword: 

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.
Keyword: