Judul: Karakteristik Fenotipe Rumput Laut Gracilaria spp. yang Dibudidaya pada Salinitas Berbeda di Tambak Desa Pantai Sederhana, Muara Gembong
Abstrak: Gracilaria spp. is an euryhaline species which can live in the marine and brackish water. Developing Gracilaria spp. in Bekasi is very potential activity because this seaweed can be cultured in ex- shrimp ponds by polyculture systems. The objective of this research is to evaluate the performance of Gracilaria spp. based on phenotype morphological characteristics and its relationship with shrimp pond water quality. Sampling was done at 3 shrimp ponds with a salinity range of 13.7-19.2 g/kg. Phenotypical characteristics Gracilaria spp. consisted of colour and thallus morfometrics, while measurement of water quality consisted of physical and chemical characters of shrimp pond. The result shows that Gracilaria spp. generally have light brown colour and at salinity higher than 13.7 g/kg the number of secondary thalluses increased, the distance between internode tertiary thallus declined, and the number of ramification index increased. Salinity showed a positive correlation with remification index which was 0.571
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Judul: eragaan Fenotipe Rumput Laut Gracilaria spp. Budidaya Polikultur Pada Salinitas 6-18 g/kg Di Tambak Muara Gembong, Bekasi
Abstrak: The phenotype diversity of seaweed Gracilaria spp. and its relationship with water quality in the ex-shrimp ponds by polyculture system was evaluated to estimate the production potential and quality. Gracilaria spp. sample was collected from 16 sampling location with a salinity range of 6.2-17.6 g/kg. Phenotypical characters observed consisted of colour and thallus morphometrics such as length of main thallus, length of secondary thallus, length of tertiary thallus, internode of secondary thallus, internode of tertiary thallus and blade. The water quality parameters included water chemistry and physics. The results showed that Gracilaria spp. colour was light brown colour and brown at salinity higher than 7.4 g/kg. Salinity affects morphometric characters significantly (P<0.35) the length of main thallus, length of secondary thallus, and the internode of secondary thallus. The salinity influence conductivity, TDS, nitrate and phosphate concentrations which associated with the growth of seaweed. The length of main thallus, length of secondary thallus, and length of tertiary thallus decreased a long with salinity increased.
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Judul: A Continuous Vaccination Strategy in the SVIR Epidemic Model
Abstrak: Vaccination is conducted to minimize the spread of a disease. The vaccination is usually done several times within a fixed time interval. In the SVIR model, it is assumed that individuals do not get immediate immunity following a vaccination program. So according to process of vaccination on SVIR model, there are two strategies, i.e. the continuous vaccination strategy (CVS) and the pulse vaccination strategy (PVS). In this study, only the CVS strategy in epidemic model SVIR is considered. Results of the study indicate that dynamics of the CVS system depends on the basic reproductive number. If the basic reproductive number is less than one, then the disease-free fixed point is asymptotically stable. It means that the disease will eventually disappear from the population. Conversely, if the basic reproductive number is greater than one, then the endemic fixed point is asymptotically stable, which means that the disease will remain exist in the population. Simulation result shows that the vaccination would minimize the spread of disease by reducing the basic reproductive number. If the time for the vaccinated recipients to obtain the immunity, as well as a possibility of vaccinated recipients to be infected are neglected, then the disease will be eradicated. This condition is called an over-evaluating effect of vaccination.
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