Judul: Pengaruh pembalakan hutan terhadap mokiriza dipterocarpaceae
Abstrak: Akibat pembalakan hutan akan mempengaruhi kondisi ling kungan yang berakibat pada kehidupan mikoriza di Hutan Dipterocarpaoeae. -Mikoriza merupakan struktur asosiasi antara akar dan fungi, dan kehadiran mikoriza pada anakan Dipterocarpaceae sangat penting. Penelitian bertujuan untuk mengetahui pengaruh pembalakan hutan terhadap mikoriza Dipterocarpaceae, spora endomikoriza pada rizosfer Dipterocarpaceae di berbagai kedalaman tanah beserta karakteristiknya. Penelitian ini merupakan studi kasus di HPH PT. Siak Raya Timber, Riau. Pengambilan contoh anakan Dipterocarpaceae, tumbuhan bawah dan tanah di sekitar rizosfer anakan Dipterocarpaceae dilakukan dengan cara garis berpetak. Lokasi pengambilan contoh anakan Dipterocarpaceae, tumbuhan bawah dan tanah tersebut adalah di hutan primer, hutan bekas tebangan 1988 dan hutan bekas tebangan 1992. ...
Keyword: Mycorrhiza dipterocardaceae

Judul: Studi Keberadaan Mikoriza di Tegakan Hutan Alam PT Inhutani II, Unit Malinau, Kalimantan Utara
Abstrak: Hutan alam Kalimantan yang didominasi oleh jenis pohon komersial, menyaratkan pertumbuhan dan performa yang baik. Salah satu faktor yang dapat membantu pertumbuhan dan performa pohon ialah mikoriza. Penelitian ini mengidentifikasi dan menganalisis keberadaan dan kolonisasi mikoriza (ektomikoriza dan mikoriza arbuskula) pada tegakan hutan alam PT Inhutani II, Unit Malinau. Keberadaan ektomikoriza diteliti dengan cara eksplorasi tubuh buah fungi dan kuantifikasi kolonisasinya. Sementara, keberadaan fungi mikoriza arbuskula (FMA) diteliti dengan melakukan identifikasi spora pada tingkat genus dan menguantifikasi kolonisasinya dengan menggunakan metode pewarnaan akar. Selain itu, informasi sifat kimiawi dan tekstur tanah pada plot penelitian juga dianalisis untuk mengetahui pengaruhnya terhadap keberadaan dan kolonisasi mikoriza. Hasil penelitian menunjukkan bahwa seluruh jenis pohon Shorea parvifolia, Shorea faguetiana, Dipterocarpus pachyphyllus, Dryobalanops lanceolata, dan Myristica sp terkolonisasi ektomikoriza dan FMA. Kolonisasi ektomikoriza ditunjukkan dengan ditemukannya tiga genus fungi pembentuk ektomikoriza (Russula, Hydnum, dan Amanita) dan kolonisasinya dengan kategori bagus (49.68 hingga 68.97%) dan sedang (46.18%). Disamping itu, ditemukan genus spora FMA (Glomus, Diversispora, Acaulospora, Entrophospora, dan Dentiscutata) dengan tingkat kolonisasi yang tinggi (>30%). Secara umum, plot penelitian memiliki kesuburan tanah yang kurang baik. Namun, nilai C-organik yang sangat tinggi (7.19%) mampu memicu keberadaan mikoriza dan menjalankan peranannya dalam siklus nutrisi tanah hutan yang menyebabkan nilai N (0.52%) berkategori sangat tingi, serta P-Bray I (12.47 ppm) dan K (0.74 cmol/kg) yang tinggi pula.
Keyword: ektomikoriza, fungi mikoriza arbuskula (FMA), hutan alam, PT Inhutani II

Judul: The Construction of Greedy SVP LLL Algorithm
Abstrak: A lattice is a set of all integer linear combination of a set of linearly independent vectors in ℝ𝑛���. The independent vectors are called bases of lattice. Any lattice can be generated from many bases, and these bases have the same cardinality. In the lattice, the most fundamental and renowned problem is the Shortest Vector Problem (SVP). SVP is a tracking problem of the shortest nonzero vector in a lattice with equivalent bases. In two dimensions, SVP problem has resolved exactly by Gauss’ algorithm. When the lattice dimension is higher than two, A.K. Lenstra, H.W. Lenstra and L. Lovasz gave a LLL algorithm to compute approximation of nonzero shortest vector in the lattice. Reduced bases solution obtained from LLL algorithm still be an approximation and has polynomial running time of arbitrary dimension which large enough. In 1994, Schnoor and Euchner modified this LLL algorithm as a new variant which later was named deep insertion LLL algorithm. This algorithm is a modified version of the LLL algorithm to the terms of the exchange step to improve the accuracy of output of LLL reduced bases and applying it to the subset sum problem. The purpose of this research are: (1) Reconstruct the LLL algorithm and deep insertion LLL algorithm using a geometric approach. (2) Construct a greedy SVP LLL algorithm. (3) Implement the three algorithms in a symbolic programming language, and evaluate them experimentally. A bases ℬ=[𝐛���1,𝐛���2,…,𝐛���𝑛���] in ℝ𝑚��� is called reduced LLL with parameter 𝛿��� if satisfies: (a) |𝜇���𝑗���𝑖���|≤12, for every integer 𝑖���,𝑗��� with 1≤𝑖���<𝑗���<𝑛���. (b)𝛿���‖𝜋���𝑗���(𝐛���𝑗���)‖2≤‖𝜋���𝑗���(𝐛���𝑗���+1)‖2, for 𝑗���=1,2,…,𝑛���−1,where 𝛿��� is a reduced parameter of real numbers with 14<𝛿���<1. The first requirement is the reduced basis 𝛿��� must “nearly orthogonal” and in its computation case, this requirement can be reached out by using the Gram-Schmidt’s orthogonalization. While the second requirement is called exchange step, or used to called as Lovasz condition. By using both of these requirements, then they establish the LLL algorithm. Then, Schnoor and Euchner modify the LLL algorithm based on the requirements of the exchange step called the deep insertion LLL algorithm, where the exchange step is based on the comparison of the projected vector in orthogonal complement [𝐛���1,𝐛���2,…,𝐛���𝑘���−1]⊥ after j-th reduction. To construct greedy SVP LLL algorithm, the requirements of the exchange step is based on purely by comparing norm of lattice 𝐛���𝑗��� with norm lattice 𝐛���𝑖��� for 𝑖���=1,2,3…,𝑗���−1. The process of insertion reduced vector after the exchange step also has done greedily. Then, we calculate the number of arithmetic operation in greedy SVP LLL algorithm for further analysis. The result of our exprimentation for three algorithms on the certain matrix size shows that the running time of the three algorithms increases propotional to the size of the matrix. The result also shows that by using 𝛿���=34 for the LLL algorithm and the deep insertion LLL algorithm, and the greedy SVP LLL algorithm which is a new variant made by using no parameter of 𝛿���, outperform of the other of two previous algorithm in terms of speed with the same output.
Keyword: LLL algorithm, LLL deep insertion algorithm, greedy SVP LLL algorithm