Judul: Quantification and Characterization of Bottom Acoustic Backscattering In Seribu Islands – Jakarta
Abstrak: Seabed has a very important role as the habitat for various living creatures, and critical part of aquatic environment. Nowadays, new methods to obtain information on bottom types, sediment characteristics and underwater vegetation in shallow water by using echosounder has flourished. In this paper, normal incident of acoustic waves were used to determine values of bottom backscattering strength (volume backscattering strength (Sv), surface backscattering strength (SS) and echo level (EL)). Sediment properties (acoustic impedance, bulk density, porosity, sound speed and sediment composition) were used to explain the acoustic measurement results. Data collection was carried out in Seribu Islands, Jakarta using SIMRAD EY 60 scientific echosounder systems with operating frequency 120 kHz. The results show that the average value of volume backscattering strength (Sv) for sand is -13,23 dB and silty sand is -21,15 dB. The average value of surface backscattering strength (SS) for sand is -23,30 dB and silty sand is -31,22 dB. The average value of echo level (EL) for sand is 177,94 ± 8,61 dB and silty sand is 167,23 ± 6,07 dB (Source Level (SL) for split beam transducer ES 120-7C series is 214 dB). These acoustics values were then used as input for PCA analysis to cluster seabed characteristics. It’s shown that the acoustic technique can be used to identify and classify sediments and map sediment provinces. Key words: sediment
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Judul: Measurement of acoustic backscattering strength of sea-bottom with single and multi beam echosounder
Abstrak: Underwater acoustic instruments has been an indispensable tool to study the ocean. Application of acoustic such as sonar technologies to bottom acoustics study has made significant advances over recent decades. The sonar systems evolved from single beam systems to more sophisticated digital ones like multi beam echo sounder. In this paper, both systems of single beam echo sounder (SBES) and multi beam echo sounder (MBES) were applied to detect and measure acoustic backscattering strength of sea-bottom. Sampling sediment was taken for ground truth data using bottom sampler. For SBES, data collection was carried out in Seribu Islands, Jakarta. Data were collected using CruzPro PcFF80 FishFinder with operating frequency 200 kHz. The algorithm to compute underwater signal using this instrument had been developed by Manik (2011). For MBES, data collection was carried out in Buyat Bay, North Sulawesi Province. Data were collected using Elac Seabeam 1050D MBES with operating frequency 180 kHz and processed with MBSystem version 5 software. For SBES, the results showed the value of surface backscattering strength (SS) for sand varied from -18.68 dB to -17.39 dB, silty sand -23.25 dB to -19.32 dB, and clayey sand was -19.83 dB. The echo level (EL) for sand varied from 131.4 dB to 138.2 dB, silty sand 133.5 dB to 135.4 dB, and for clayey sand was 136.5 dB (using source level (SL) 163 dB). For MBES, the SS for silty sand varied from -24.26 dB to -20.56 dB, and sandy silt -25.12 dB to -24.30 dB.
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Judul: Respons Ketahanan Sepuluh Kultivar Mentimun (Cucumis sativus L.) terhadap Infeksi Tobacco mosaic virus
Abstrak: Tobacco mosaic virus (TMV) merupakan salah satu virus yang baru dilaporkan dapat menginfeksi tanaman mentimun. Informasi mengenai respons ketahanan tanaman mentimun terhadap infeksi TMV belum ada, sehingga penelitian ini bertujuan menguji respons ketahanan sepuluh kultivar komersial mentimun terhadap infeksi TMV. TMV diinokulasi secara mekanis pada sepuluh kultivar mentimun. Peubah penyakit yang diamati yaitu waktu inkubasi, tipe gejala, insidensi, keparahan penyakit, indeks keparahan penyakit dan titer virus, serta peubah agronomi yaitu tinggi tanaman, jumlah daun, dan jumlah bunga. Titer virus dideteksi dengan metode DAS-ELISA menggunakan antiserum spesifik TMV. Hasil penelitian menunjukkan waktu inkubasi pada tanaman uji berkisar dari 6.9˗12.4 hari setelah inokulasi (HSI) dengan insidensi penyakit berkisar 30-100% tergantung kultivar. Tanaman yang terinfeksi TMV menunjukkan gejala bervariasi dari mosaik ringan hingga berat. Skor keparahan berkisar dari 1.8˗3.0 dengan indeks keparahan penyakit berkisar 0.1-33.3 dan titer virus berkisar dari 0.266˗0.646. Secara umum, Infeksi TMV kurang menghambat pertumbuhan tinggi tanaman, namun mengurangi jumlah daun pada kultivar Yupiter dan jumlah bunga pada kultivar Alicia F1, Baby 007 F1, Yupiter secara signifikan. Berdasarkan parameter yang diamati, kultivar Vanesa F1 dan Kancil dikategorikan sebagai kultivar tahan, kultivar Naya F1, Panda, Wulan F1, dan Yupiter dikategorikan toleran, serta kultivar Alicia F1, Baby 007 F1, Maestro, dan Monza F1 dikategorikan rentan terhadap infeksi TMV.
Keyword: Gejala mosaik, inokulasi mekanis, ketahanan, titer virus