Fragmentation of Random Trees

We study fragmentation of a random recursive tree into a forest by repeated removal of nodes. The initial tree consists of N nodes and it is generated by sequential addition of nodes with each new node attaching to a randomly-selected existing node. As nodes are removed from the tree, one at a time, the tree dissolves into an ensemble of separate trees, namely, a forest. We study statistical properties of trees and nodes in this heterogeneous forest, and find that the fraction of remaining nodes m characterizes the system in the limit N --> infty. We obtain analytically the size density phi_s of trees of size s. The size density has power-law tail phi_s ~ s^(-alpha) with exponent alpha=1+1/m. Therefore, the tail becomes steeper as further nodes are removed, and the fragmentation process is unusual in that exponent alpha increases continuously with time. We also extend our analysis to the case where nodes are added as well as removed, and obtain the asymptotic size density for growing trees.Comment: 9 pages, 5 figure

Extensions of Effective Medium Theory of Transport in Disordered Systems

Effective medium theory of transport in disordered systems, whose basis is the replacement of spatial disorder by temporal memory, is extended in several practical directions. Restricting attention to a 1-dimensional system with bond disorder for specificity, a transformation procedure is developed to deduce, from given distribution functions characterizing the system disorder, explicit expressions for the memory functions. It is shown how to use the memory functions in the Lapace domain forms in which they first appear, and in the time domain forms which are obtained via numerical inversion algorithms, to address time evolution of the system beyond the asymptotic domain of large times normally treated. An analytic but approximate procedure is provided to obtain the memories, in addition to the inversion algorithm. Good agreement of effective medium theory predictions with numerically computed exact results is found for all time ranges for the distributions used except near the percolation limit as expected. The use of ensemble averages is studied for normal as well as correlation observables. The effect of size on effective mediumtheory is explored and it is shown that, even in the asymptotic limit, finite size corrections develop to the well known harmonic mean prescription for finding the effective rate. A percolation threshold is shown to arise even in 1-d for finite (but not infinite) systems at a concentration of broken bonds related to the system size. Spatially long range transfer rates are shown to emerge naturally as a consequence of the replacement of spatial disorder by temporal memories, in spite of the fact that the original rates possess nearest neighbor character. Pausing time distributions in continuous time random walks corresponding to the effective medium memories are calculated.Comment: 15 pages, 11 figure

Variabilitas Suhu Dan Salinitas Di Laut Halmahera

Suhu dan salinitas memiliki peranan penting dalam mencerminkan kondisi massa air dan secara langsung berpengaruh terhadap kondisi biologi dan kimia perairan. Tujuan penelitian ini adalah menganalisis dinamika angin di perairan Laut Halmahera dan mendiskripsikan kondisi suhu dan salinitas permukaan laut (SPL) di Laut Halmahera. Data yang digunakan yaitu data penginderaan jauh Marine Copernicus untuk data Suhu dan salinitas sedangkan data angin dari ECMWF. Pengolahan data menggunakan software ODV untuk mengolah data SPL dan salinitas dari tahun 2016-2020, selanjutnya data angin diolah menggunakan software surfer 16. Laut Halmahera memiliki suhu permukaan laut berkisar antara 26.20 - 31.6°C dimana kondisi maksimum terjadi bulan Mei dan November. Sedangkan salinitas berkisar antara 29.38 - 34.9 psu, dimana kondisi maksimum pada bulan Desember sampai Maret. Dinamika angin di Laut Halmahera mempengaruhi pola sebaran suhu permukaan laut dan salinitas yang ada pada perairan tersebut, dimana kecepatan angin berkisar antara 6.5 - 2.5 m/s

THE Pb AND Cd CONCENTRATIONS IN MANGROVE SUBSTRATE OF AMBON BAY

The mangrove ecosystem is one of the potential coastal ecosystems in Ambon Bay waters, most of which are in Inner Ambon Bay.Threats to the mangrove ecosystem in the waters of Ambon Bay are the activities that take place around it. Moreover, several rivers that empty into Ambon Bay cause the entry of debris/waste from land. Previous studies have shown that Pb and Cd have been detected in seawater in Ambon Bay waters, so it is considered important to conduct research on mangrove ecosystem sediments. The purpose of this study was to determine the concentration of heavy metals (Pb and Cd) in sediments in the mangrove ecosystem of Ambon Bay. The sampling points of the sediment in mangrove ecosystems were carried out using purposive sampling method. Sample analysis was carried out at the Environmental Productivity Laboratory of IPB using the Nitric Acid-Perchloric Acid Digestion method. The results showed that the concentration of heavy metal Plumbum (Pb) ranged from 18.25-35.98 mg/kg and Cadmium (Cd) 1.57-2.70 mg/kg. The results showed that the concentration of heavy metal Plumbum (Pb) ranged from 18.25-35.98 mg/kg and Cadmium (Cd) 1.57-2.70 mg/kg. Based on the results of the analysis, it can be said that, although Pb was found in fairly high concentrations, it had not yet exceeded the toxic threshold, while Cd had approached the toxic threshold. Overall, it can be concluded that the sediment has been contaminated with heavy metals Pb and Cd but has not affected the mangrove ecosystem, and is an indication that natural filtration occurs.Salah satu potensi ekosistem pesisir yang cukup luas ada di perairan Teluk Ambon Dalam adalah ekosistem mangrove. Ancaman bagi ekosistem mangrove yang ada di perairan Teluk Ambon adalah aktivitas yang berlangsung di sekitarnya (antropogenik). Adanya beberapa sungai yang bermuara di Teluk Ambon menjadi pendukung masuknya buangan/limbah dari darat. Logam berat Pb dan Cd telah terdeteksi pada air laut di perairan Teluk Ambon, sehingga dianggap penting untuk melakukan penelitian pada sedimen ekosistem mangrove. Tujuan dari penelitian ini adalah untuk mengetahui konsentrasi logam berat (Pb dan Cd) dalam sedimen pada ekosistem mangrove Teluk Ambon. Penentuan titik pengambilan sampel sedimen pada ekosistem mangrove dilakukan dengan menggunakan metode purposive sampling. Analisis sampel dilakukan dengan menggunakan metode Nitric Acid-Perchloric Acid Digestion. Hasil penelitian menunjukkan bahwa konsentrasi logam berat Plumbum (Pb) berkisar antara 18,25-35,98 mg/kg dan Cadmium (Cd) 1,57-2,70 mg/kg. Hasil analisis menunjukkan bahwa, Pb walaupun didapati dalam konsentrasi yang cukup tinggi namun belum melampaui ambang batas toksik, sementara Cd telah mendekati ambang batas toksik. Secara keseluruhan dapat disimpulkan bahwa, sedimen telah terkontaminasi logam berat Pb dan Cd namun belum berpengaruh pada ekosistem mangrove, dan merupakan indikasi bahwa terjadi filtrasi alami. &nbsp

Effects of disorder in location and size of fence barriers on molecular motion in cell membranes

The effect of disorder in the energetic heights and in the physical locations of fence barriers encountered by transmembrane molecules such as proteins and lipids in their motion in cell membranes is studied theoretically. The investigation takes as its starting point a recent analysis of a periodic system with constant distances between barriers and constant values of barrier heights, and employs effective medium theory to treat the disorder. The calculations make possible, in principle, the extraction of confinement parameters such as mean compartment sizes and mean intercompartmental transition rates from experimentally reported published observations. The analysis should be helpful both as an unusual application of effective medium theory and as an investigation of observed molecular movements in cell membranes.Comment: 9 pages, 5 figure

Pemanfaatan Kompos Ela Sagu, Sekam dan Dedak sebagai Media Perbanyakan Agens Hayati Trichoderma Harzianum Rifai.

The use of biological agents to prevent the growth of plant diseases is aimed at decreasing the capability of particular pathogen, preventing their growth and spread, reducing the infection and intensity of pathogenic attack to main plants. Trichoderma harzianum is commonly found in almost all types of soil, and is one of fungi that can be used as biological agents to control plant pathogens. Growth and development of this fungi are mostly influenced by factors such as temperature, light, air, and pH. It is also dependents on other nutrients such as carbon, nitrogen and plain carbohydrate which are contained in sago waste (ela), bran and rice husk. The objective of this study is to find out the utilization of sago waste, bran and rice husk as media to multiply the biological agents T. harzianum. The result of this study showed that sago waste compost could be used as a medium to multiply the antagonist T. harzianum; when appropriately mixed with bran and rice husk (1:1:1 v/v), sago waste composts would be an effective media to develop the T. harzianum fungus. This mixture is better compared to sago waste composts, husk, sago waste composts and bran, and sago waste composts and husk. It is doe to the fact that in the media number of spore of T. harzianum (7,08 x 109/mL) increased and colony characteristics was dense.

Molecular motion in cell membranes: analytic study of fence-hindered random walks

A theoretical calculation is presented to describe the confined motion of transmembrane molecules in cell membranes. The study is analytic, based on Master equations for the probability of the molecules moving as random walkers, and leads to explicit usable solutions including expressions for the molecular mean square displacement and effective diffusion constants. One outcome is a detailed understanding of the dependence of the time variation of the mean square displacement on the initial placement of the molecule within the confined region. How to use the calculations is illustrated by extracting (confinement) compartment sizes from experimentally reported published observations from single particle tracking experiments on the diffusion of gold-tagged G-protein coupled mu-opioid receptors in the normal rat kidney cell membrane, and by further comparing the analytical results to observations on the diffusion of phospholipids, also in normal rat kidney cells.Comment: 10 pages, 5 figure

PEMANFAATAN TEKNOLOGI INDERAJA UNTUK PENINGKATAN EKONOMI NELAYAN DI DESA LILIBOY

Remote sensing technology has developed very rapidly and has a very significant role in the fisheries and marine sector as a provider of data and information. Liliboy Country is a coastal village located on the island of Ambon which has very productive waters with potential for fishing activities. This Community Service is made in the form of counseling, with the aim of introducing technological knowledge and providing information about fishing areas, as well as developing skills for the fishermen of Liliboy village to get more effective and efficient catches. It is hoped that the fishing community of Liliboy village will understand the use of sensing technology to determine fishing areas so that it will grow the community's economy and improve the welfare of lif