Judul: Vertical Distribution of Coral Bleaching in Pulau Pramuka Marine Protected Area Kepulauan Seribu
Abstrak: Fenomena pemanasan global merupakan isu yang sangat penting saat ini, fenomena ini menyebabkan dampak ekologis terhadap ekosistem pesisir termasuk terumbu karang. Penelitian ini bertujuan untuk menganalisis distribusi vertikal coral bleaching di Area Perlindungan Laut Pulau Pramuka, Kepulauan Seribu. Metode yang digunakan meliputi pengambilan data lapangan, analisis kondisi terumbu karang, dan identifikasi tingkat pemutihan karang dengan metode survey cepat berdasarkan buku Panduan Pemutihan Karang 2016 pada berbagai kedalaman yaitu kedalaman 5 meter, 10 meter dan 15 meter serta kesehatan karang berdasarkan metode CoralWatch. Hasil penelitian menunjukkan bahwa coral bleaching lebih intens terjadi pada kedalaman dangkal dibandingkan dengan kedalaman yang lebih dalam. Komposisi bentuk pertumbuhan tertinggi adalah Coral Foliose dan Coral Mushroom serta komposisi genera tertinggi adalah Pachyseris sp. dan Pleuractis sp. dengan kasus pemutihan yang tinggi.
Keyword: Ekosistem Terumbu Karang, bleaching, Coral Reef Ecosystem, kesehatan

Judul: Spatial Variability of Coral Coverage in the Waters of North Seribu Islands District, DKI Jakarta
Abstrak: Terumbu karang membutuhkan waktu yang lama untuk pulih dan rentan terhadap kerusakan. Penelitian ini bertujuan untuk menganalisis variabilitas spasial tutupan terumbu karang berdasarkan kategori pemanfaatan yang berbeda di Perairan Kepulauan Seribu Utara. Penelitian ini dilaksanakan pada bulan Agustus 2022 di enam stasiun pengambilan sampel di Perairan Kepulauan Seribu Utara. Pengambilan data tutupan karang diestimasi menggunakan metode Line Intercept Transect, sampel kualitas air yang diambil meliputi parameter kecerahan, nitrat, oksigen terlarut, pH, dan salinitas. Kategori pemanfaatan yang berbeda antar- stasiun pengambilan sampel tidak berpengaruh nyata terhadap besar persen tutupan karang hidup, kecuali pada stasiun yang berkategori dilindungi. Penyebab utama yang mempengaruhi nilai persen tutupan terumbu karang antar-stasiun pengambilan sampel diduga karena kerusakan fisik akibat benturan secara langsung dari aktivitas manusia, seperti kegiatan penangkapan, pariwisata, dan transportasi. Tutupan karang tertinggi dengan kategori baik terdapat pada Area Perlindungan Laut, sementara tutupan karang terendah dengan kategori rusak terdapat di Barat Pulau Pramuka sebagai stasiun yang paling terpengaruh oleh aktivitas manusia., Coral reefs take a long time to recover and prone to damage. This study aims to analyze the spatial variability of coral reef coverage based on different utilization categories in the Waters of the North Seribu Islands District. This study was conducted in North Seribu Islands District that divided into six sampling points in August 2022. The coral coverage data collection was estimated using the Line Intercept Transect method, the water quality samples taken were brightness, nitrate, dissolved oxygen, pH, and salinity. Different utilization categories between sampling stations have no significant effect on coral cover percentage, except for protected categorized station. The main cause affecting the coral coverage is suspected to be due to physical damage caused by direct impacts from human activities, such as fishing, tourism, and transportation activities. The highest coral coverage in the good category was in the Marine Protected Area, while the lowest coral coverage in the damaged category was in West Pramuka Island as the location most affected by human activities.
Keyword: Kepulauan Seribu, kualitas perairan, terumbu karang, coral reef, Seribu Islands, water quality

Judul: Algorithm Construction of HLI Hash Function
Abstrak: Cryptography is a study of mathematical techniques related to aspects of information security regarding on confidentiality, data integrity, entity authentication, and data origin authentication. Data integrity is a service, which is associated with the conversion of data carried out by unauthorized parties. To maintain data integrity, one can use hash functions. An hash function is a computationally efficient function to map an arbitrary length bitstring to a fixed length bitstring called as hash value. The use of hash function in maintaining the information integrity and authentication is in digital signatures, virus protection, and software distribution. Illustration of the hash function in the integrity and authentication of information that is emailed as follow. The sender sends the information and hash value to the recipient. If the hash value of the information is equal to the hash value that is sent by the sender, then information has not been changed. Otherwise the information has been changed. An hash function has two properties, one way and collision resistance. An hash function is called one way if it is computationally infeasible to find any input such that when given any hash value . Meanwhile an hash function is called collision resistant if it is computationally infeasible to find any two inputs where such that . The purpose of this study is to construct a HLI hash function algorithm, to analyze the speed and security of the hash functions as a results of construction. Furthermore, it is to compare it with SWIFFT. Hash function is constructed based on the result of algebraic operations on modular polynomial ringwith . Modular polynomial ring noted as is a set of all polynomials of degree at most with coefficients in . can be represented as a set of integer vector of modulo in dimension . So, it is simple to implement in a computer. In vector operations, is lattice . Furthermore, alattice that is defined from certain polynomial ring is called ideal lattice. HLI hash function is consists of addition and multiplication algorithm in the ring. Addition algorithm consists of sumation operations of modulo and multiplication consists of multiplication operations of modulo . Generally, algorithm of HLI hash function consists of multiplication operations of modulo and addition operations of modulo . However, if the input is binary number then multiplication algorithm only consists of multiplication operation of modulo , so algorithm of HLI hash function consists of multiplication operations of modulo and addtion operations of modulo . An hash function is secured if it has two properties, i.e., one way and collision resistance. HLI hash function hash is one way, it is following the proof of Micciancio. It is has collision resistant because of polynomial is irreducible over and monic. Moreover, it is proved that for every unit vector , the vector is small vector. If the input of hash function is a binary number then HLI hash function only involves addition operations of modulo . So the time that used almost same with SWIFFT. The excellence of HLI hash function is the key size smaller than SWIFFT. This effect on
Keyword: hash function, modular polynomial ring, lattice