Judul: Praktek Budidaya dan Persepsi Petani Ubi Kayu Terhadap Hama Kutu Putih Phenacoccus manihoti di Kabupaten Bogor
Abstrak: A survey of cassava farmers’ practices and perception of the cassava mealybug, Ph. manihoti, was conducted in three villages of District of Bogor in February-April 2013. A semi-structured questionnaire was used to elicit information from 60 cassava farmers. The respondents were mostly middle aged (30-50 years old), and most had elementary education. Farm size was mainly smallholdings (≤ 3.000 m2) with a status as tenants. Although they have planted cassava for 10-20 years, they were not a member of the farmer groups. This might due to absence of contact with the extension agents. Most of the farmers planted cassava year around. Cassava varieties grown consisted of Manggu and Roti, and the yield were sold to tapioca factory in the area. Most farmers reported that Phenacoccus manihoti was found for the first time attacking cassava in 2010, and led to 50% yield losses. Therefore, integrated pest management program (IPM) for this new pest should be developed by considering the socio-economic factors of the farmers.
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Judul: Analysis of Factors Affecting Interest of Young Farmer Families to Work in Cassava Farming (Case Study: Benteng Village, Ciampea District, Bogor Regency)
Abstrak: Kabupaten Bogor termasuk dalam kawasan khusus pengembangan ubi kayu berdasarkan Keputusan Menteri Pertanian No. 03/Kpts/PD. 120/1/2015. Salah satu penghasil ubi kayu Kabupaten Bogor terletak di Desa Benteng, Kecamatan Ciampea. Ubi kayu menjadi komoditas unggulan dan sumber pendapatan bagi petani di Desa Benteng. Petani ubi kayu didominasi oleh petani berumur tua, hal ini diindikasi karena kurangnya ketertarikan generasi muda Desa Benteng terhadap usahatani ubi kayu sehingga perlunya regenerasi untuk keberlanjutan usahatani ubi kayu di Desa Benteng. Penelitian ini bertujuan untuk (1) menganalisis persepsi pemuda keluarga tani terhadap usahatani ubi kayu di Desa Benteng, (2) menganalisis pendapatan usahatani ubi kayu di Desa Benteng, (3) menganalisis faktor-faktor yang memengaruhi minat pemuda keluarga tani untuk bekerja pada usahatani ubi kayu di Desa Benteng. Metode analisis data yang digunakan adalah skala likert, analisis pendapatan, dan regresi logistik biner. Hasil penelitian menunjukkan bahwa persepsi pemuda secara keseluruhan terhadap usahatani ubi kayu memiliki persepsi positif atau setuju namun tidak setuju terhadap kategori risiko usahatani ubi kayu. Nilai R/C rasio lebih dari satu yang artinya usahatani ubi kayu di Desa Benteng menguntungkan. Faktor-faktor yang berpengaruh secara signifikan terhadap minat pemuda keluarga tani pada usahatani ubi kayu adalah jenis kelamin, pendapatan usahatani orang tua dan pengalaman usahatani., Bogor Regency is included in a special area for cassava development based on the Decree of the Minister of Agriculture No. 03/Kpts/PD. 120/1/2015. One of the centers of cassava in Bogor Regency is located in Benteng Village, Ciampea District. Cassava is a leading commodity and source of income for farmers in Benteng Village. Cassava farmers are dominated by old age farmers, this is indicated because of the lack of interest of the younger generation of Benteng Village towards cassava farming so that regeneration is needed for the sustainability of cassava farming in Benteng Village. This study aims to (1) analyze the perception of young farming families on cassava farming in Benteng Village, (2) analyze the income of cassava farming in Benteng Village, (3) analyze the factors that influence the interest of young farming families to work in cassava farming. wood in the Fort Village. Data analysis methods used are Likert scale, income analysis, and binary logistic regression. The results showed that the youth's overall perception of cassava farming had a positive perception or agreed but disagreed with the risk category of cassava farming. The value of the R/C ratio is more than one, which means that cassava farming in Benteng Village is profitable. Factors that significantly influence the interest of young farming families in cassava farming are gender, parents' farm income and farming experience.
Keyword: binary logistic regression, cassava, income analysis, perception, Likert scale

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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