Judul: Modeling The Dependency of Stock Index Before and During the Covid-19 Pandemic
Abstrak: Pandemi Covid-19 merupakan peristiwa ekstrem yang saat ini terjadi di dunia. Pandemi Covid-19 menyebabkan lumpuhnya berbagai aktivitas perokonomian sehingga berdampak pada jatuhnya pasar saham. Oleh karena itu, pemodelan peristiwa ekstrem sangat penting untuk memprediksi kerugian besar yang terjadi di bidang keuangan. Copula nilai ekstrem merupakan metode yang tepat untuk menggambarkan hubungan kebergantungan antar aset saat peristiwa ekstrem. Dalam karya ilmiah ini, data yang digunakan adalah data imbal hasil indeks saham IHSG, STI, dan KLSE dari 1 Januari 2019 hingga 1 Oktober 2020. Data tersebut kemudian dikategorikan menjadi dua periode yaitu sebelum Covid-19 dan saat Covid-19. Dari data tersebut dibuat model ARMA-GARCH untuk mengatasi autokorelasi dan heteroskedastisitas. Kemudian ditentukan copula terbaik untuk data pada periode sebelum Covid-19 dan copula nilai ekstrem terbaik untuk data pada periode Covid-19. Copula t-Student dipilih sebagai copula terbaik untuk data pada periode sebelum Covid-19. Copula nilai ekstrem terbaik yang dipilih untuk ketiga indeks adalah copula Gumbel., The Covid-19 pandemic is an extreme event that is currently occurring in the world. The Covid-19 pandemic paralyzed various economic activities, resulting in the collapse of the stock market. Therefore, modeling of extreme events is very important to predict big losses in the financial sector. The extreme value copula is an appropriate method to measure the dependency between assets during extreme events. In this scientific work, the data used are return stock index of IHSG, STI, and KLSE from January 1, 2019 to October 1, 2020. Then, the data are categorized into two periods, before Covid-19 and during Covid-19. Form these data, an ARMA-GARCH model was created to overcome autocorrelation and heteroscedasticity. Then, the best copula was determined for data in the period before Covid-19 and the best extreme value copula for data in the Covid-19 period. The t-Student copula was chosen as the best copula for data in the period before Covid-19. The best extreme value copula chosen for the three indices is the Gumbel copula.
Keyword: Copula, Covid-19, Extreme Value Copula, Stock Index

Judul: The Effect of Stringency Index and Macroeconomic Variables on Stock Movements during The Covid-19 Pandemic: Empirical Evidence from 50 Countries
Abstrak: Pandemi Covid-19 menjadi isu yang penting saat ini dan berdampak pada perekonomian dan pasar saham. Untuk menangani dampak pandemi ini, terdapat respon pemerintah yang berbeda antar negara sehingga dilakukan perbandingan keketatan respon pemerintah dengan stringency index. Untuk menganalisis bagaimana keketatan respon pemerintah dan variabel makroekonomi terhadap pergerakan saham selama pandemi Covid-19, maka dilakukan penelitian dengan data cross section yang terdiri dari 50 negara dan data time series bulanan periode 2020-2021. Metode yang digunakan adalah panel statis dan dinamis, sehingga ditemukan model terbaik yaitu panel statis dengan random effect model. Hasil pada penelitian yaitu pengaruh stringency index terhadap pergerakan saham positif dan signifikan yang berarti semakin ketat respon pemerintah dalam menangani dampak pandemi Covid-19 maka indeks saham akan meningkat. Inflasi dan nilai tukar berpengaruh positif signifikan dan pertumbuhan jumlah uang yang beredar berpengaruh positif tetapi tidak signifikan pada pergerakan saham., The Covid-19 pandemic is a crucial issue today and impacts the economy and the stock market. There are different government responses between countries to deal with the impact of this pandemic, so a comparison of the tightness of the government's response with a stringency index is carried out. This paper analyzes the government's response and macroeconomic variables to stock movements during the Covid-19 pandemic using cross-section data of 50 countries and time-series monthly data for the 2020-2021 period. The method used is static and dynamic panel. The best model is a static panel with a random effect model. The results is the effect of the stringency index is positive and significant to stock movements, which means that the tighter the government's response in dealing with the impact of the Covid-19 pandemic, the stock index will increase. Inflation and exchange rates have a significant positive effect and money growth has a positive but not significant impact on stock movements.
Keyword: Dynamic Panel, Macroeconomics, Pandemic, Stock Market, Static Panel, Stringency Index

Judul: Membran Selulosa Berbahan Dasar Kulit Buah Nanas sebagai Adsorben Zat Warna Tekstil Biru Metilena
Abstrak: Treatment of various fruit pineapple in daily life created a problem of the environment, such as build up of peel waste. The waste could be transformed further to microbial cellulose (nata de pina) by using microorganisms Acetobacter xylinum. The application of microbial cellulose produced flux of 4.72-65.56 L/m2.h. The rejection membrane of methylene blue was 90 - 98 %, meaning that the membrane was able to adsorb methylene blue. Based on analysis using Fourier transform infrared and scanning electrone microscope the membrane composed of cellulose, with the type of asymmetry, and has pore size 20-50 nm as ultrafiltration membrane.
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