Judul: Analisis Model Pandemik dan Prepandemik Avian Influenza pada Populasi Manusia
Abstrak: Avian influenza is a viral disease caused by a virus within the subtype of H5N1 in which its transmission caused by birds or human. In human population, transmission process of avian influenza is discussed in the model called: bird model, prepandemic model and pandemic model. The bird model has two equlibrium points. These are saddle disease free equilibrium and stable endemic equilibrium. The endemic equlibrium occurred when the reproduction number of avian influenza is greater than one. In the endemic equilibrium, avian influenza may infect both bird and human. The prepandemic model has two equilibrium points. These are avian influenza dominant equilibrium and human influenza dominant equilibrium. The human influenza dominant equilibrium occurred when the reproduction number of human influenza is greater than one. The pandemic model has one pandemic equlibrium. The human influenza pandemic occurred when the ratio of human influenza invasion, pandemic invasion and the reproduction number of human influenza is greater than one, respectively. The avian influenza pandemic occurred when the ratio of human influenza invasion, pandemic invasion is less than one and the reproduction number of avian influenza greater than one, respectively.
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Judul: Analysis of the Stability of Influenza Spread Model with Disease Resistance in Humans
Abstrak: Influenza adalah penyakit pada sistem pernapasan yang disebabkan oleh virus influenza. Pada penelitian ini, dibahas model SEIR yang menggambarkan penularan virus influenza dengan memerhatikan faktor resistensi penyakit pada manusia, yaitu suatu kondisi individu yang terpapar, terinfeksi dan sembuh kembali menjadi individu yang rentan. Berdasarkan model matematika tersebut diperoleh bilangan reproduksi dasar (ℛ0) dan dua titik tetap yaitu, titik tetap bebas penyakit dan titik tetap endemik . Analisis kestabilan titik tetap ditentukan dengan menggunakan kriteria Routh-Hurwitz dan fungsi Lyapunov. Analisis sensitivitas terhadap ℛ0 menghasilkan parameter laju kontak transmisi penyebaran virus influenza dan laju transmisi populasi manusia terpapar ke populasi manusia rentan sebagai parameter yang paling berpengaruh terhadap kenaikan bilangan reproduksi dasar. Peningkatan bilangan reproduksi dasar terjadi saat laju kontak transmisi penyebaran virus influenza diperbesar dan laju transmisi populasi manusia terpapar ke populasi manusia rentan diperkecil. Hal ini mengakibatkan kondisi endemik secara cepat terjadi sehingga pengendalian penyebaran penyakit influenza dapat dilakukan dengan mengurangi laju kontak transmisi dan meningkatkan laju transmisi populasi manusia terpapar ke populasi manusia rentan., Influenza is a disease of the respiratory system caused by the influenza virus. In this study, a SEIR model that depicts the transmission of the influenza virus is discussed by considering the factor of disease resistance in human, which is a condition of the individuals who are exposed, infected and recovered that can turn back into a susceptible individual. Based on this mathematical model, the basic reproduction number (ℛ0) is obtained. The model has two fixed points, which consist of one disease free and one endemic fixed points. Stability analysis of the fixed points are determined by using the Routh-Hurwitz criterion and the Lyapunov function. Sensitivity analysis to ℛ0 shows that the parameters of the contact rate of virus transmission and the transmission rate of the exposed to susceptible human are the most influencing parameters for the basic reproduction number. The increase of the basic reproduction number occurs when the contact rate of virus transmission is enlarged and the transmission rate of the exposed to susceptible human is reduced. It causes the endemic condition to occured rapidly. Therefore, controlling the spread of influenza virus should be done by reducing the contact rate of virus transmission and increasing the transmission rate of the exposed to susceptible human.
Keyword: basic reproduction number, disease resistance, Lyapunov, sensitivity  analysis   

Judul: Elektrodeposisi Film Tipis Semikonduktor Cu2ZnSnS4 (CZTS) pada Substrat Kaca ITO
Abstrak: Semiconductor Cu2ZnSnS4 (CZTS) thin film that can be used as absorber layers on solar cell module was made via electrodeposition method. CZTS thin film was electrodeposited on the surface of a silicate glass coated with a thin layer of indium tin oxide (ITO). Deposition process was done using potentiostatic mode at room temperature with a potential of 1.05 V for 30, 45, and 60 minutes, followed with annealing the film at 2 different temperatures, 500 ºC using furnace and 180 ºC using hot plate, both treatments for 45 minutes in N2/H2S atmosphere. The X-ray difractograms were analyzed using Match 2 program and showed that the CZTS thin films had kesterit crystalline structure, with a low percentage of CZTS phase. The thin film also contained secondary phases such as Cu2S, ZnS, and SnS. The obtained CZTS thin films had a thickness between 1.039 and 1.676 μm. Absorption study showed that the band gap energy of CZTS thin films which was annealed using furnace ranged from 1.50 to 1.52 eV, whereas that annealed using the hot plate was not observed. The band gap energy value showed that CZTS thin films can be used as sunlight absorber layers on solar cell. The formation of CZTS crystal film on this investigation was effectively performed using furnace annealing process at a temperature of 500 ºC with deposition time of 45 minutes.
Keyword: Thin film, Electrodeposition, Cu2ZnSnS4