Judul: The Relationship between Nutritional Knowledge and the Intensity of Online Food Purchasing with Diet Quality and Nutritional Status of IPB Female Students
Abstrak: Meningkatnya intensitas penggunaan aplikasi pesan antar makanan online tidak hanya memberikan dampak baik namun juga dampak yang dapat merugikan pada gaya hidup dan kesehatan. Sistem penggunaan aplikasi yang memberikan akses sebesar-besarnya dapat berdampak pada tidak terkontrolnya jenis dan jumlah makanan yang dibeli. Penelitian ini bertujuan menganalisis hubungan pengetahuan gizi dan intensitas pembelian makanan secara online dengan kualitas diet serta status gizi mahasiswi IPB. Penelitian ini dilakukan pada Februari-Maret 2023 dengan menggunakan desain penelitian cross sectional, melibatkan 95 subjek mahasiswi aktif IPB yang dipilih secara purposive sampling. Pengumpulan data dilakukan melalui wawancara dan self-administrated secara online. Data antropometri diperoleh melalui pengukuran langsung. Analisis data menggunakan Microsoft Excel 2010 dan IBM SPSS Statistics 21. Tidak terdapat hubungan yang signifikan antara pengetahuan gizi dengan intensitas pembelian makanan secara online dan kualitas diet, serta kualitas diet dengan status gizi (p>0,05). Namun, terdapat hubungan yang signifikan antara pengetahuan gizi dan kualitas diet yang dinilai menggunakan metode DQI-I (p<0,05). Mahasiswi disarankan untuk memperhatikan pola makannya dengan mengonsumsi makanan sesuai prinsip gizi seimbang dan memperhatikan variasi, kecukupan, serta mengurangi konsumsi makanan berdensitas energi tinggi untuk menjaga kualitas diet dan status gizi., The increasing intensity of using online food delivery applications has not only had a good but also a detrimental impact on lifestyle and health. An application system that provides maximum access can have an impact on uncontrolled types and amounts of food purchased. This study aimed to analyze the relationship between the intensity of online food purchasing and nutritional knowledge with diet quality and nutritional status of IPB female students. This research was conducted in February-March 2023 using a cross-sectional research design, involving 95 active female students of IPB who were selected by purposive sampling. Data collection was carried out through interviews and self-administered online. Anthropometric data obtained through direct measurements. Data analysis used Microsoft Excel 2010 and IBM SPSS Statistics 21. There was no significant relationship between nutritional knowledge and the intensity of online food purchases and diet quality, as well as diet quality and nutritional status (p>0.05). However, there was a significant relationship between nutritional knowledge and diet quality that assessed using the DQI-I method (p<0,05). Female students are advised to pay attention to their diet by consuming food according to the principles of balanced nutrition and paying attention to variety, adequacy, and reducing consumption of high energy density foods to maintain diet quality and nutritional status.
Keyword: diet quality, female students, nutritional knowledge, nutritional status, online food purchasing

Judul: Relationship between Intensity of  Using Online Food Delivery Applications and Physical Activity with College  Student’s Nutritional
Abstrak: Meningkatnya intensitas penggunaan pesan antar online serta rendahnya aktivitas fisik selama pandemi Covid-19 dapat memberi dampak yang buruk bagi kesehatan. Intensitas penggunaan aplikasi pesan antar online dan status gizi berhubungan dengan tingkat ekonomi seseorang. Penelitian ini bertujuan untuk menganalisis hubungan antara intensitas penggunaan aplikasi pesan antar makanan online, aktivitas fisik, uang saku, dan pendapatan keluarga dengan status gizi selama pandemi Covid-19. Desain penelitian ini adalah cross sectional dengan jumlah sampel 94 subjek mahasiswa aktif IPB yang dipilih secara purposive sampling. Pengumpulan data dilakukan melalui wawancara dan self-administrated secara online. Tidak terdapat hubungan yang signifikan antara status gizi dengan intensitas penggunaan aplikasi pesan antar makanan online aktivitas fisik, uang saku, dan pendapatan keluarga (p>0,05). Pengguna aplikasi pesan antar makanan online agar dapat mengontrol pemesanan makanan dan meningkatkan aktivitas fisik walau hanya di dalam rumah agar memiliki pola hidup yang lebih sehat.
Keyword: covid-19, nutritional status, online food delivery application, physical activity

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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