Judul: Penyusunan persamaan penduga volume pohon kelompok jenis Dipterocarpaceae di PT Timberdana Kalimantan Timur
Abstrak: Tree volume estimation especially standing tree, still a practical problem for the forester. Tree volume table is a common way to describe the relation between tree volume and its estimation variables (tree diameter or height). Berkhout model (V = aDb ; where : V = volume, D = diameter breast height, a dan b = constans) is a simple tree volume estimator because only use single variable which is tree diameter (D). It is one of many models with clear thought structure, mathematically derivated from cylinder volume using form factor (Suhendang 1993). Berkhout model is a non linear model which usually it should be transformed to linear model using logaritmic transformation to find regression constans. Statistical softwares development today, made that’s a problem no more. This research aims (1) to find better accuracy for tree volume estimation using Berkhout model, by transformation or without transformation; and (2) to find the best tree volume model for dipterocarpacea in PT Timberdana Kalimantan Timur. Data used in this research consist of 96 tree samples of dipterocarpaceae in PT Timberdana, East Kalimantan. Data divided into two data sets for model building (63 tree) and validation (33 tree). Data used in this research gives that Berkhout model equation built using transformation to linear model (V = 0.000411D2.214) has a better accuracy than model without transformation. The best tree volume equation of dipterocarpaceae in PT Timberdana is exponential association model, expressed by the equation : V = -3.920*(1.386  e-0.0142D), while Berkhout model is in second place together with quadratic fit and sinusoidal fit models.
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Judul: Tree Volume Estimation for Pinus (Pinus merkusii Jungh et de Vriese) at Gunung Walat Educational Forest Sukabumi, Jawa Barat.
Abstrak: Kegiatan pengelolaan hutan memerlukan informasi tentang potensi tegakan yang dapat diproduksi untuk dapat memenuhi kebutuhan kayu di pasaran. Penaksiran volume pohon dengan menggunakan tabel volume adalah yang paling sering digunakan untuk menggambarkan hubungan antara volume pohon dengan peubah bebasnya (diameter dan tinggi pohon). Tabel volume dibuat berdasarkan persamaan volume yang disusun dengan persamaan regresi. Persamaan regresi terbaik biasanya dipilih dari berbagai macam persamaan yang dicobakan terhadap data yang dimiliki. Dari sekian banyak persamaan regresi yang dapat dicoba, persamaan Berkhout: V = aDb (di mana : V = volume pohon ; D = dbh ; a, b = konstanta), adalah persamaan regresi yang sederhana karena hanya menggunakan satu peubah bebas saja yaitu diameter setinggi dada (dbh). Persamaan Berkhout adalah persamaan non linier, yang pendugaan koefisien regresinya biasanya melalui transformasi (logaritma) menjadi persamaan linier. Penelitian ini bertujuan untuk: (1) Memperoleh cara penyusunan persamaan pohon dengan menggunakan persamaan Berkhout yang lebih akurat melalui transformasi atau tanpa transformasi; (2) Memperoleh persamaan penduga volume pohon Pinus di Hutan Pendidikan Gunung Walat Sukabumi. Berdasarkan data yang digunakan dalam penelitian ini, persamaan volume Berkhout melalui transformasi (V = 0.0001259D2.5400) memiliki tingkat akurasi lebih baik dibandingkan tanpa transformasi. Persamaan atau model penduga volume terbaik untuk jenis Pinus (Pinus merkusii Jungh et de Vriese) di Hutan Pendidikan Gunung Walat Sukabumi adalah model Gompertz Relation dengan bentuk persamaan V=10,3265 x -ee^(1,9928-0.0339D).
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Judul: Durability of Specific Immunoglobulin (Ig) Y Againts Influenza and Covid-19 in Sunscreen
Abstrak: The benefit of specific immunoglobulin Y (Ig Y) as an active ingredient in personal care products such as sunscreen has not been properly studied. Our study aims to evaluate the reliability of specific IgY against influenza and the COVID-19 virus in a sample sunscreen product. Specific IgY influenza and COVID-19 viruses were inserted in the sample sunscreen at two concentrations of 0.1% and 0.25%. Three treatments were observed: control (C) sunscreen without IgY, treatment 1 (T1) sunscreen with 0.1% IgY, and treatment 2 (T2) sunscreen with 0.25% IgY. Organoleptic observations were carried out to monitor changes in aroma, color, and texture, and sunscreen sampling was done every week for 6 weeks. The durability of IgY was evaluated using an enzyme-linked immunosorbent assay (ELISA) and a neutralization assay. Organoleptic observation from weeks 1 to 6 showed consistency in its aroma, color, and texture. Enzyme-linked immunosorbent assay and neutralization assay (NA) results of the T1 and T2 groups showed negative results except for sample T1 at week 5, which showed a positive result in the Influenza A ELISA. Based on the results, it seems that IgY concentrations of 0.1% or 0.25% were not optimal. However, this negative result might be due to low concentration of the IgY and the presence of beeswax, which inhibits IgY and causes it to dissolve in distilled water, thus preventing it from being detected in the assay.
Keyword: Immunoglobulin Y, Sunscreen, Influenza, COVID-19, Biological Activity