Judul: The Effect of Products, Prices, and Online Consumer Reviews on Consumer Purchase Decisions on Health Products Through ECommerce in Greater Jakarta During the Covid-19 Pandemic
Abstrak: Pandemi yang masih berlanjut membuat produk kesehatan menjadi barang yang paling dicari konsumen di E-Commerce. Tujuan penelitian ini adalah (1) Mengidentifikasi karakteristik konsumen dalam melakukan pembelian produk kesehatan pada masa pandemi Covid-19 melalui E-Commerce (2) Menganalisis pengaruh produk, harga, dan online consumer review terhadap keputusan pembelian konsumen pada produk kesehatan di E-Commerce. Data pada penelitian ini adalah data primer dan sekunder. Data primer diperoleh dari pengisian kuesioner oleh responden yang pernah melakukan pembelian produk kesehatan melalui ECommerce selama pandemi Covid-19 sesuai kriteria yang ditentukan. Data sekunder diperoleh dari buku, internet, dan jurnal yang relevan dengan penelitian ini. Teknik sampling yang digunakan untuk meperoleh sampel adalah nonprobability sampling yakni voluntary sampling. Analisis data dilakukan dengan analisis deskriptif dan analisis regresi linear berganda. Hasil penelitian menunjukkan produk, harga, dan online consumer review berpengaruh secara signifikan positif dan simultan terhadap keputusan pembelian.
Keyword: analisis regresi linear berganda, produk, harga, online consumer review

Judul: The Effect of Online Consumer Review and Rating  on Purchase Intention of Health Products on Shopee E-Marketplace During the  Covid-19 Pandemic in Jabodetabek
Abstrak: Pandemi COVID-19 menyebabkan peningkatan pembelian produk-produk kesehatan seperti masker, handsanitizer, obat-obatan dan lain-lain. Shopee merupakan salah satu e-marketplace yang sedang berkembang di Indonesia dan menyediakan fitur online consumer review dan rating pada platformnya. Penelitian ini bertujuan untuk menganalisis pengaruh online consumer review dan rating terhadap minat beli produk kesehatan pada e-marketplace Shopee selama masa pandemi COVID-19 di Jabodetabek. Penarikan sampel dilakukan dengan teknik purposive sampling. Metode yang digunakan dalam penelitian ini adalah analisis deskriptif dan SEM-PLS. Hasil analisis menunjukkan variabel online consumer review dan rating berpengaruh positif dan signifikan terhadap minat beli produk kesehatan dengan variabel rating memiliki pengaruh lebih dominan., COVID-19 pandemic led to an increase in purchases of health products such as masks, handsanitizers, medicines and others. Shopee is one of the growing online marketplaces in Indonesia that provides online consumer review and rating features on its. This study aimed to analyze the effect of online consumer review and rating on purchase intention of health products on shopee online marketplace during the COVID-19 pandemic. The sampling method used in this study was purposive sampling technique. The method used in this research was descriptive analysis and SEM-PLS. The results of the analysis show that online consumer review and rating variables have a positive and significant effect on purchase intention in health products with the rating variable as the dominant influence.
Keyword: Health Products, Online Consumer Review, Purchase Intention, Rating, Shopee

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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