Judul: Indonesian Stock Market Reaction to the  Russia-Ukraine Invasion (Case Study of Wheat-Based Product Issuers)
Abstrak: Perang antara Rusia dan Ukraina mengakibatkan adanya pembatasan ekspor bagi Rusia dan kerusakan fasilitas serta blokade pada pelabuhan menyebabkan Ukraina tidak bisa melakukan kegiatan ekspor. Kemudian berdampak pada fluktuasi harga komoditas gandum global akibat gangguan rantai pasok komoditas dari kedua negara yang merupakan produsen sekaligus eksportir penting gandum global. Oleh karena itu, pengumuman invasi Rusia terhadap Ukraina berpotensi mengandung information content yang relevan sehingga berpotensi memengaruhi keseimbangan harga pasar dan pada akhirnya terjadilah reaksi pasar. Tujuan dari penelitian ini adalah untuk menganalisis reaksi pasar saham Indonesia yang ditinjau dari abnormal return pada emiten produk berbahan gandum serta perbedaan abnormal return dan trading volume activity sebelum dan sesudah pengumuman. Metode penelitian yang digunakan yaitu event study dengan periode pengamatan (t-10, t+10). Terdapat sembilan emiten yang dipilih melalui teknik purposive sampling. Hasil penelitian menunjukkan bahwa saham emiten produk berbahan gandum di pasar saham Indonesia bereaksi negatif melalui abnormal return mulai sebelum peristiwa hingga sesudah peristiwa selama periode jendela yang ditetapkan. Hasil uji beda menunjukkan bahwa tidak terdapat perbedaan yang signifikan pada abnormal return antara sebelum dan sesudah pengumuman. Berbeda halnya dengan trading volume activity yang menunjukkan hasil bahwa terdapat perbedaan yang signifikan antara sebelum dan sesudah pengumuman., The war between Russia and Ukraine resulted in export restrictions for Russia, and the damage to facilities and blockade of ports caused Ukraine to halt its export activities. Consequently, this had an impact on the fluctuation of global wheat commodity prices due to disruptions in the commodity supply chain from both countries, which are important producers and exporters of wheat globally. Therefore, the announcement of Russia's invasion of Ukraine potentially contains relevant information content that could influence market price equilibrium, ultimately leading to market reactions. The aim of this study is to analyze the Indonesian stock market's reaction, specifically the abnormal return of wheat-based product issuers, and to examine the differences in abnormal return and trading volume activity before and after the announcement. The research method used is an event study with an observation period of (t-10, t+10). Nine issuers were selected using purposive sampling technique. The research findings indicate that the stocks of wheat-based product issuers in the Indonesian stock market reacted negatively, showing abnormal returns both before and after the event during the designated observation period. The test results show that there is no significant difference in abnormal return between before and after the announcement. However, in contrast, the trading volume activity shows a significant difference between before and after the announcement.
Keyword: abnormal return, event study, market reaction, trading volume activity, wheat-based issuers

Judul: The Effect of Restrictive Policy of  Wheat Demand in Indonesia
Abstrak: Indonesia merupakan salah satu negara pengimpor gandum terbesar di dunia. Indonesia belum dapat memproduksi gandum secara mandiri sehingga untuk memenuhi tingginya permintaan pasar diperlukan kebijakan impor. Tujuan dari penelitian ini yaitu menganalisis pengaruh hambatan kebijakan impor gandum terhadap volume permintaan gandum di Indonesia dari Australia, Kanada, Ukraina, Amerika Serikat dan Rusia. Metode yang digunakan dalam penelitian ini yaitu analisis data panel dengan spesifikasi model pengaruh tetap dan model gravitasi. Komoditas yang diteliti adalah gandum dengan kode HS 1001. Hasil estimasi menunjukkan bahwa variabel yang berpengaruh signifikan yaitu harga gandum internasional, GDP negara pengekspor, nilai tukar riil, jarak ekonomi dan dummy hambatan impor tarif dan non tarif. Sedangkan, variabel yang tidak berpengaruh secara signifikan adalah GDP negara importir dan populasi. Alternatif kebijakan yang didapatkan yaitu implementasi kebijakan kuota impor akan lebih baik daripada tarif impor, tarif impor berisiko meningkatkan harga gandum di pasar. Selain itu, pemerintah perlu melakukan penelitian dan pengembangan produksi gandum nasional bersama lembaga terkait agar gandum dapat diproduksi secara efisien., Indonesia is one of the largest wheat importers countries in the world. Indonesia has not been able to produce wheat independently and must import to meet the high demand. This study aimed to analyze the barriers effect of wheat import policy on wheat demand volume in Indonesia with exporting countries such as Australia, Canada, Ukraine, the United States, and Russia. The method used in this research is panel data analysis with fixed effect model specifications and gravity models. The commodity studied was wheat with HS code 1001. The estimation results showed that the significant effect variables were international wheat prices, GDP of exporting countries, real exchange rates, economic distance, and tariff and non-tariff import barriers. Besides, the importing country's GDP and the population were variables with insignificant effect. The alternative policy obtained was the import quota policy implementation would be better than the import tariff. Import tariff has the risk of increasing the price of wheat in the market. Therefore, the government needs to carry out national wheat production research and development with related institutions for efficient wheat production.
Keyword: Fixed effect model, Gravity model, Import barrier, Wheat

Judul: Categorization in Macaca fascicularis.
Abstrak: Categorization is an ability to group individuals or events into different classes mediated by conceptualized mental images. There are several levels of categorization and within a taxonomy the levels are nested. At the most concrete level of categorization, all or most members of the category shared common physical attributes that differ from other categories. The higher the level of category, the fewer common attributes between members of the group. In addition to humans, the ability to categorize has also been proposed in animals. One example of categorization in animal is species discrimination. Using matching-tosample task, present experiment tested ability of the long-tailed macaque (Macaca fascicularis) in discriminating dichotomous-stimuli of different animals. The species has been shown to be able to see photos as representations of real object so I used facial photos of humans and animals for the stimuli. First, I tested their ability to classify humans and macaques into separate group. Second, I tested their ability to discriminate their conspecific from other macaques. And the last, I tested whether the subjects were able to discriminate non-human animals from humans. In all of these experiments I found that the subjects showed high performance in categorizing objects, even when I discarded details of visual informations, such as color and local shapes. The ability to identify objects with reduced representation of physical properties means the subjects were able to generalize attributes of members of the group. This would indicate that the subjects created a higher level abstraction. On the other hand, in discriminating intrageneric macaque species I found that they were able to extract uniqueness of each species. More over, I also found that the subjects were able to put photos of non-human animals that shared very few similarities in physical percepts into one group. I suggested that the subjects could create a more abstract concept based on non-percepts relations as a basis to put the objects into one category. Thus, I concluded that M. fascicularis were able to perform multiple levels of categorizations.
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