Judul: Sebaran Bivariate Inverse Weibull
Abstrak: Sebaran baru dapat dibangun dari sebaran lain yang telah ada. Salah satu cara yang umum digunakan adalah menggabungkan dua atau lebih sebaran untuk mendapatkan sebaran baru. Pada karya ilmiah ini akan dibahas suatu sebaran baru yaitu sebaran bivariate inverse Weibull yang dibangun dari dua pasang sebaran inverse Weibull yang saling bebas. Menggunakan definisi sebaran maksimum, fungsi sebaran kumulatif bersama dan fungsi kepekatan peluang bersama dari sebaran bivariate inverse Weibull dapat dirumuskan dari fungsi sebaran inverse Weibull. Pendugaan parameter dilakukan dengan metode penduga kemungkinan maksimum dan metode Newton-Raphson. Pembangkitan serangkaian data dengan jumlah yang berbeda menunjukkan data dengan jumlah besar memberikan dugaan yang lebih akurat bagi parameter., A new distribution can be built from already existing distributions. One of the common method is compounding two or more distributions to obtain a new one. This paper will discuss a new distribution that is a bivariate inverse Weibull distribution. This new distribution is built from two pairs of independent inverse Weibull distributions. Using the definition of maximum distribution, the joint cumulative distribution function and the joint probability density function of a bivariate inverse Weibull can be formulated from the inverse Weibull distribution function. Parameter estimation was done using the maximum likelihood method and Newton-Raphson method. Generating several sets of data with different amounts pointed out that a large number data gave more accurate estimates for parameters.
Keyword: bivariate inverse Weibull distribution, maximum distribution, inverse Weibull distribution, maximum likelihood method, Newton-Raphson method

Judul: Penghitungan Sebaran Gabungan Poisson-Generalized Inverse Weibull dengan Metode Simulasi Monte Carlo
Abstrak: Sebaran gabungan digunakan untuk menentukan besarnya risiko total yang mungkin terjadi dalam periode waktu tertentu. Sebaran ini diperoleh dengan menggabungkan sebaran claim frequency dan sebaran claim severity. Jika banyaknya klaim menyebar Poisson dan besarnya klaim menyebar Generalized Inverse Weibull, maka sebaran gabungannya tidak mudah ditentukan secara analitik. Oleh karena itu, dalam karya ilmiah ini digunakan metode simulasi Monte Carlo untuk memperoleh pendekatan dari sebaran gabungan tersebut. Kemudian, dengan menggunakan sebaran gabungan hampiran tersebut, dapat dihitung nilai dugaan dari dua ukuran risiko, yaitu Value at Risk (VaR) dan Tail Value at Risk (TVAR).
Keyword: generalized inverse Weibull, sebaran gabungan, simulasi Monte Carlo, Tail Value at Risk, Value at Risk

Judul: Growth, Concentration Chlorophyll-a, and Structure of Macroalgae Gracilaria edulis in the Culture Media Containing Copper
Abstrak: The physiological responses (specific growth rate, concentration of chlorophyll-a, morphological and anatomical structure of the vegetative cells) of the marine macroalga Gracilaria edulis at the different concentrations of copper (0.01 as control, 0.04, 0.06 and 0,5 ppm) delivered continuously for 28 days under controlled laboratory conditions were investigated. Result showed that the degree of copper toxicity depends on both factor the concentration and exposure time. Copper concentration and day of exposure decreased significantly the specific growth rate (SGR) of the Gracilaria edulis but only 0,5 ppm Cu decreased the chlorophyll-a content when compared to control. Of the various physiological end points measured, growth proved to be the most sensitive response than chlorophyll-a with reductions in specific growth rate (SGR). The reason for this could be related to a greater sensitivity of the enzymes involved in growth than those related to chlorophyll-a or a greater energy needs to maintain cellular integrity and metabolic processes under sublethal Cu stress. In all cases, the main effect on vegetative cells were structure changes in cortex and subcortex cells, compared to control, macroalgae exposed to copper showed depigmentation and blending in the lateral branches, heavy staining of the cell wall and severe damage of cell membrane, while the mucilage and the cell walls was densely fibrillar, thick and heavily stained, the cortex cell was clearly vacuolated, the presence of endophytic on the cell wall and endophytic spores in the mucilage. The presence vacuoles should be related to a metal immobilization mechanism, minimizing the Cu toxicity for cells. The epiphytic bacteria can act as a biofilter diminishing the availability of Cu for macroalgae accumulation.
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