Judul: Frequency and Risk of Consuming Processed Smoked Stingray Fish on the North Coast of Java Island
Abstrak: Ikan pari asap merupakan salah satu olahan populer di Indonesia. Penelitian ini bertujuan menentukan frekuensi konsumsi olahan ikan pari asap di sembilan daerah utara Pulau Jawa, yaitu Lamongan, Tegal, Jakarta, Surabaya, Kendal, Batang, Indramayu, Demak, dan Pemalang, menghitung cemaran merkuri (Hg) dan metil merkuri (MeHg), menghitung tingkatan cemaran Polycylic Aromatic Hydrocarbon (PAH), dan menentukan risiko konsumsi olahan ikan pari asap. Penentuan cemaran dengan Inductively Coupled Plasma Mass Spectrometry (ICP-MS) untuk merkuri, Gas Chromatography Mass Spectrometry (GC-MS) untuk PAH dan Liquid Chromatography Inductively Coupled Plasma Mass Spectrometry (LC-ICP-MS) untuk metil merkuri. Uji logam berat menunjukkan sampel produk tercemar merkuri berada di atas batas aman konsumsi menurut Standar Nasional Indonesia (SNI). Hasil uji PAH menunjukkan sampel berada di bawah batas aman konsumsi menurut SNI. Hasil perhitungan Hazard Question (HQ) dan Hazard Index (HI) > 1, menunjukkan bahwa responden yang terkena dampak mungkin menghadapi risiko kesehatan non-karsinogenik.
Keyword: Logam berat, Frekuensi konsumsi, Risiko konsumsi

Judul: Risk Assessment of Commercial Smoked Shark Consumption
Abstrak: Merkuri merupakan jenis logam berat yang dapat memberikan dampak negatif bagi tubuh. Bentuk merkuri yang paling toksik adalah metil merkuri. Ikan hiu memiliki kemungkinan mengandung merkuri yang tinggi akibat biomagnifikasi. Indonesia merupakan salah satu pemasok utama hiu di dunia. Bentuk olahan ikan hiu adalah hiu asap. Pengasapan dapat menghasilkan senyawa polisiklik aromatik hidrokarbon (PAH) yang diantaranya bersifat karsinogen. Penelitian bertujuan menentukan tingkat cemaran merkuri, metil merkuri, PAH, dan menghitung analisis risiko konsumsi hiu asap. Metode penelitian meliputi uji merkuri, metil merkuri dan kandungan PAH pada ikan hiu asap dan penyebaran kuesioner. Seluruh sampel mengandung merkuri dengan 4 sampel yang melebihi ambang batas (1 ppm). Kandungan metil merkuri terdeteksi pada 6 sampel dengan 3 sampel yang melebihi batas (1 ppm). Kandungan PAH pada sampel terdeteksi dengan jumlah yang tidak melebihi batas maksimum. Hasil analisis risiko menunjukkan nilai Hazard Index (HI) >1 yang berarti risiko dari mengonsumsi hiu asap adalah signifikan dan kronis., Mercury is a type of heavy metal that can have a negative impact on the body. The most toxic form of mercury is methylmercury. Sharks are likely to contain high levels of mercury due to biomagnification. Indonesia is one of the main suppliers of shark in the world. The processed form of shark is smoked shark. Smoking can produce polycyclic aromatic hydrocarbon (PAH) compounds, some of which are carcinogens. The study aims to determine the level of mercury, methyl mercury, PAH, and calculate the risk analysis of smoked shark consumption. Research methods included testing mercury, methylmercury and PAH content in smoked shark and distributing questionnaires. All samples contained mercury with 4 samples exceeding the threshold (1 ppm). Methylmercury was detected in 6 samples with 3 samples exceeding the limit (1 ppm). PAH content in the samples was detected with an amount that did not exceed the maximum limit. The results of the risk analysis showed a Hazard Index (HI) value >1, which means that the risk from consuming smoked shark is significant and chronic.
Keyword: heavy metal, hazard index, chronic

Judul: Bifurkasi Hopf pada Model Siklus Bisnis Kaldor Kalecki tanpa dan dengan Waktu Tunda
Abstrak: Business cycle model is one of dynamical system models in economic. One of the business cycles model is Kaldor-Kalecki model. Kaldor-Kalecki business cycle model that is written in delayed defferential equations, is a business cycle model that involves gross product and capital stock of a company. In this paper Kaldor-Kalecki business cycle model is analyzed using both nondelay and delay in time of capital stock. By Taylor expansion for the time delayed model, an analysis of stability around the fixed points has been done. Furthermore, by using Hopf bifurcation theorem, it can be shown that there exists periodic orbits and limit cycle. In the nondelayed model, changing the parameter of goods market could lead to the occurrence of Hopf bifurcation and the existence of limit cycle. Similarly, for the delayed model, it has been shown that changing the time delay parameter may result in the occurrence of Hopf bifurcation and limit cycle.
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