Judul: Analisis Perbandingan Sistem Pajak di Indonesia dengan Australia dalam Perspektif Ekonomi Politik
Abstrak: Tax plays an important role as a source to finance the development of the country, although if the tax ratio and the number of individual taxpayers in Indonesia are compared with other countries, the tax revenue in Indonesia is not optimal yet. This research aims to know about factor that can increase the number of individual taxpayers in Indonesia comparison to Australia. Furthermore the connection between tax system, democracy, and rent-seeking activity; also the effect to tax revenue are analysed. The method is Panel Data Analysis in 15 countries of G-20 include Indonesia and Australia. Data used in this research are tax revenue as percentage of GDP, Democracy Index, Paying Taxes Ranking, and International Country Risk Guide (ICRG) Index from 2008 until 2011. The best model is Fixed Effect Model with cross section weights and white cross section. The estimation shows that a good tax system, full democracies, and the absent of rent-seeking have a significant and positive effect to tax revenue.
Keyword: Panel Data, Rent-Seeking, Democracy, Tax system

Judul: Hubungan antara Tarif Pajak Penghasilan dan Penerimaan Pajak: Analisis Data Negara-negara ASEAN 1987-2011
Abstrak: Penerimaan negara dari pajak memiliki kontribusi terbesar dalam pembiayaan operasional pemerintah dibandingkan dengan sumber pendanaan lainnya. Tujuan penelitian ini untuk menganalisis efektivitas instrumen distribusi pendapatan, yaitu persentase tarif pajak (tax rate) yang optimal dalam memaksimalkan penerimaan. Adapun tingkat optimal tax rate Indonesia dianalisis dengan membandingkan beberapa negara ASEAN, seperti Malaysia, Singapura dan Thailand serta faktor lain yang memengaruhinya, yaitu tax ratio, pertumbuhan ekonomi dan GDP per kapita. Data yang digunakan adalah data sekunder dari perekonomian masing-masing negara pada periode 1987-2011. Hasil dari analisis data panel menggunakan estimasi model fixed effect didapatkan nilai R2 0.9438 yang menandakan bahwa variasi dari perubahan variabel dependen mampu dijelaskan secara serentak oleh variabel-variabel independen sebesar 94.38 persen. Sisanya sebesar 5.62 persen dijelaskan oleh faktor lain yang tidak masuk dalam model. Tax ratio, pertumbuhan ekonomi dan GDP per kapita memiliki pengaruh positif terhadap penerimaan pajak di negara ASEAN.
Keyword: ASEAN, ketimpangan, panel data, tax rate, tax ratio

Judul: Natrium lignosulfonat sebagai agen pendispersi pada mortar
Abstrak: Lignosulphonate, a modification product of lignin waste from pulp and paper industry can be used as water reducer in mortar mixture. This substance can influence the mechanical characteristic of mortar such as diameter of flow, flexural strength, compressive strength, and setting time of cement paste. Lignosulphonate shows it function as dispersant on cement hydration at 3 days that analyzed with x-ray difractometer. Research result show that flow of fresh mortar rise with increase concentration (from weight of cement) of synthetic sodium lignosulphonate (NaLS). It show that mortar homogenity also increasing. The result of flexural strength and compressive strength test use synthetic NaLS 0.1-0.3% from weight of cement show that addition synthetic NaLS 0.2% is the best result because it has the biggest of flexural strenght and compressive strength value. Initial setting time of cement paste increase, about 50% with addition of synthetic NaLS 0.2%. Whereas the final setting time decrease, about 8%. Cement hydration test show increase hydration product peak, Ca(OH)2 dan calcium silicate hydrate (C-S-H).
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