Judul: Preference and Availability of Vegetable, Fruit, and Supplement Consumption at Adolescents in Jakarta During Covid-19 Pandemic
Abstrak: Konsumsi sayur dan buah yang cukup merupakan salah satu hal penting untuk memperkuat sistem daya tahan tubuh manusia terutama pada masa pandemi covid-19. Kebutuhan vitamin, mineral, dan serat dapat diperoleh dari makanan dan suplemen, karena tubuh tidak dapat memproduksinya secara cukup. Penelitian ini dilakukan dengan tujuan menganalisis preferensi dan ketersediaan terhadap konsumsi sayur, buah, dan suplemen pada remaja di Jakarta saat masa pandemi covid-19. Desain penelitian yang digunakan yaitu cross-sectional study. Pengumpulan data dilakukan dengan pengisian kuesioner dan FFQ secara daring self-administered. Pengambilan data dilakukan pada bulan Oktober 2020 dengan subjek sebanyak 64 orang. Hasil penelitian menunjukkan bahwa sebagian besar subjek memiliki preferensi yang baik terhadap konsumsi sayur, buah, dan suplemen (90,6%). Sebagian besar subjek memiliki ketersediaan yang baik terhadap sayur, buah, dan suplemen (95,3%). Laki-laki mengonsumsi sayur dan buah lebih baik (r=-0,219, p=0,080), selain itu semakin tua responden semakin kurang konsumsi sayur dan buahnya (r=-0,214, p=0,089). Semakin tinggi tingkat pendidikan subjek, semakin kurang konsumsi sayur dan buah (r=-0,298, p=0,017). Semakin baik preferensi seseorang, semakin sering mengonsumsi suplemen (r=0,902, p=0,016) dan semakin baik ketersediaan, semakin sering mengonsumsi suplemen (r=0,221, p=0,079), Sufficient consumption of vegetables and fruit is one of the important things to strengthen immune system mainly during covid-19 pandemic. Vitamin, mineral, and fiber requirements are attainable from food and supplement, because the body cannot produce them sufficiently. This research aimed to analyze the preference and availability of vegetable, fruit, and supplement consumption at adolescents in Jakarta during the covid-19 quarantine. The design of this research was a cross-sectional study. Data collection consisted of filling out online self-administered questionnaire and FFQ. The data was collected in October 2020 with 64 subject. The research represent that subjects mostly had a good preference for vegetable, fruit and supplement consumption (90,6%). Most of the subjects had a good availability of vegetable, fruit, and supplement (95,3%). Male were more often consumption of vegetable and fruit (r=-0,219, p=0,080), meanwhile the older subjects represent the less consumption of vegetable and fruit (r=-0,214, p=0,089). The higher level of education of the subject means less consumption of vegetable and fruit (r=-0,298, p=0,017). More better person's preference means more frequent the supplement (r=0,902, p=0,016) and more better availability of the subjects represent more frequent consume supplements (r=0,221, p=0,079).
Keyword: adolescent, availability, preference, supplement consumption, vegetable-fruit consumption

Judul: Factors Related with Vegetables and Fruits Consumption among IPB University Students During the Distance  Learning Period
Abstrak: Pandemi covid-19 menyebabkan diterapkannya sistem Pembelajaran Jarak Jauh (PJJ) pada mahasiswa IPB yang juga mengubah pola konsumsi makanannya termasuk sayur dan buah. Tujuan penelitian ini ialah mengetahui faktor-faktor yang berhubungan dengan konsumsi sayur dan buah pada mahasiswa IPB selama PJJ. Penelitian ini dilakukan pada November 2020 menggunakan desain studi cross sectional dengan metode pengambilan sampel non-probability accidental sampling yang melibatkan 66 subjek dari mahasiswa semester 3 IPB. Faktor-faktor yang menjadi fokus penelitian ini ialah karakteristik subjek, karakteristik sosial ekonomi keluarga subjek, ketersediaan sayur dan buah di rumah, suku subjek, wilayah tempat tinggal, preferensi sayur dan buah, serta waktu mengenal sayur dan buah. Terdapat hubungan signifikan negatif konsumsi sayur dengan pendidikan ayah (p=0,020, r=-0,287) serta hubungan signifikan positif konsumsi buah dengan preferensi buah (p=0,000, r=0,000). Terdapat perbedaan signifikan konsumsi sayur antara subjek yang tinggal di kota dengan subjek yang tinggal di desa (p=0,039)., The COVID-19 pandemic led to the implementation of the Distance Learning (PJJ) system for IPB students who also changed their food consumption patterns, including vegetables and fruit. The purpose of this study to know the related factors with the vegetables and fruit consumption among IPB University students during PJJ. This research was conducted in November 2020 using a cross sectional study design with a non-probability accidental sampling method involving 66 subjects from 3rd semester students. The factors that become a focus of this research are the subject characteristics, socio-economic of subject's family, the availability of vegetables and fruit at home, the subject's ethnicity, the residential area, preferences of vegetables and fruits, and the time to know vegetables and fruits. There is a significant negative relationship of vegetable consumption with father's education (p=0.020, r=-0.287) and a significant positive relationship of fruit consumption with fruit preference (p=0.000, r=0.000). There was a significant difference of vegetable consumption between subjects who living in cities and subjects living in villages (p=0.039).
Keyword: college student, distance learning, vegetable and fruit consumption

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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