Structure Of Mangrove Community On Kumo Island Tobelo Subdistrict, North Halmahera Regency

Mangroves are unique plants because they are able to survive in extreme areas with high salinity levels. Mangroves are also often referred to as tidal plants because their growth is influenced by tides. This study uses the quadrant transect line method by determining 3 observation points (stations) taking samples, and determining the condition of mangroves, the calculation of species density, species frequency, species closure, importance value index, and diversity. For environmental variables, several measurements were made, namely temperature, salinity, and type of substrate on Kumo Island. From the results of the study, it is known that mangrove species that have a high density are R.apiculata species and the highest frequency value is in the same species S.alba, while the value of diversity shows a moderate value. The temperature range on Kumo Island is around 29-30 C, as well as the salinity range of 29-30 ppt, and the dominating substrate which is muddy, causes the S.alba species to be found more than other species. Keywords: Kumo Island, Community Structure, Mangrove Abstrak Mangrove merupakan tumbuhan yang unik dan khas karena mampu bertahan hidup pada daerah yang ekstrim dengan kadar salinitas yang tinggi. Mangrove juga sering disebut dengan tumbuhan pasang surut karena pertumbuhanya dipengaruhi oleh pasang surut .Penelitian ini mengunakan metode line transek kuadran dengan menentukan 3 titik pengamatan (stasiun) pengambilan sempel,dan untuk mengetahui kondisi mangrove maka dilakukan perhitungan kerapatan jenis, frekuensi jenis, penutupan jenis, indeks nilai penting dan keanekaragam. Untuk variabel lingkungan dilakukan beberapa pengukuran yaitu suhu, salinitas dan tipe substrat yang ada di Pulau Kumo. Dari hasil penelitian diketahui jenis mangrove yang memiliki kerapatan tinggi yaitu jenis R.apiculata  dan untuk nilai frekuensi tertingi ada pada jenis S.alba, sedangkan untuk nilai  tutupan ada pada jenis S.alba, untuk keanekaragam menunjukan nilai yang sedang. Kisaran suhu di Pulau Kumo  yaitu sekitar 29-30 C, sama halnya dengan kisaran salinitas yaitu 29-30 ppt dan untuk substrat yang mendominasi yaitu berlumpur,hal ini menyebabpkan jenis S.alba banyak ditemukan dari pada jenis yang lain. Kata kunci: Pulau Kumo, Struktur Komonitas, Mangrov

Direction of light propagation to order G^2 in static, spherically symmetric spacetimes: a new derivation

A procedure avoiding any integration of the null geodesic equations is used to derive the direction of light propagation in a three-parameter family of static, spherically symmetric spacetimes within the post-post-Minkowskian approximation. Quasi-Cartesian isotropic coordinates adapted to the symmetries of spacetime are systematically used. It is found that the expression of the angle formed by two light rays as measured by a static observer staying at a given point is remarkably simple in these coordinates. The attention is mainly focused on the null geodesic paths that we call the "quasi-Minkowskian light rays". The vector-like functions characterizing the direction of propagation of such light rays at their points of emission and reception are firstly obtained in the generic case where these points are both located at a finite distance from the centre of symmetry. The direction of propagation of the quasi-Minkowskian light rays emitted at infinity is then straightforwardly deduced. An intrinsic definition of the gravitational deflection angle relative to a static observer located at a finite distance is proposed for these rays. The expression inferred from this definition extends the formula currently used in VLBI astrometry up to the second order in the gravitational constant G.Comment: 19 pages; revised introduction; added references for introduction; corrected typos; published in Class. Quantum Gra

Gastropod Community An Vertical Distribution Pattern Of Littoraria Scabra (Linnaeus, 1758) In Mangrove Ecosystem, Tombariri District, Nort Sulawesi

The Coast water of Tombariri District is an area that has a main ecosystem like mangroves, seagrass, and reef.  This research is to aim to know the species various, the structure of the gastropod community, and the vertical distribution pattern of Littoraria scabra in the mangrove ecosystem in Tombariri District, North Sulawesi.  Process of gastropod sampling horizontally where transects were put horizontal coastline on every location including Mokupa, Elu, and Tambala.   Every transect long has 65 m and also has every transect has 15 quadrats where every quadrat is one-meter square. Therefore, every transect has 15 quadrats, so a total of 45 quadrats. Every quadrant was put systematic method, that is, at terrestrial closing mangrove of 5 quadrats, middle mangrove of 5 quadrats, and coast close mangrove of 5 quadrats.  Process of sampling particularly L.scabra where taking vertically, especially on microhabitats that is, roots, stems, branches, and leaves of mangroves. High measuring by meter unit,  conducted from the ground where L.scabra found at mangrove until the top vegetation.  Based on the result of observation on the identification of gastropod sampling found in the mangrove ecosystem, Tombariri District, North Sulawesi as many 235 of individuals consisting of 5 orders, 23 families, and 32 genera having 78 species.  The density of species on every location Mokupa, Elu and Tambala, that is, (D) = 4.60, 5.47, and 5.60 in ind/m2, index of diversity,(H) = 2.54, 3.07, and 3.51 and index of dominance, ID = 0.04, 0.07 and 0.13. Keywords: Microhabitat, density, diversity, and dominance Abstrak Perairan pantai Kecamatan Tombariri merupakan daerah yang memiliki ekosistim utama pesisir seperti mangrove, lamun, dan terumbu karang. Penelitian ini bertujuan untuk mengetahui jenis-jenis, struktur komunitas gastropoda dan pola distribusi vertikal spesies Littoraria scabra di ekosistem mangrove Kecamatan Tombariri, Sulawesi Utara. Proses pengambilan sampel gastropoda secara horizontal, di mana transek ditempatkan sejajar garis pantai pada setiap lokasi yakni di Mokupa, Elu, dan Tambala. Panjang setiap transek 65 m dan setiap transek memiliki 15 kuadrat di mana kuadrat berukuran 1 x 1 m.  Setiap transek punya 15 kuadrat sehingga total  kuadrat seluruh transek adalah 45 kuadrat. Penempatan kuadrat menggunakan metode sistematik yaitu di bagian darat 5 kuadrat, pertengahan 5 kuadrat  dan  mangrove pinggir  laut 5 kuadrat. Proses pengambilan sampel secara vertikal khusus Littoraria scabra, di mikrohabitat akar, batang, cabang dan daun mangrove,Sementara pengambilan sampel L.scabra diukur ketinggian di mana spesies Littoraria scabra ditemukan ldi pohon mangrove dengan menggunakan meteran, dimulai dari dasar sampai ke ujung pohon mangrove. Berdasarkan hasil pengamatan dan identifikasi sampel gastropoda yang ditemukan di ekosistem mangrove Kecamatan Tombariri, Sulawesi Utara ditemukan sebanyak 235 individu yang terbagi ke dalam 5 ordo, 23 famili dan 32 genera dari 78 spesies. Kepadatan Jenis pada masing-masing lokasi = 4,60, 5,47, dan 5,60 ind/m2. Keanekaragaman H’= 2,54, 3,07, dan 3,51. Dominansi C= 0,04, 0,07, dan 0,13. Kata Kunci : Mikrohabitat, Kepadatan, Keanekaragaman, Dominansi

Structure Of Mangrove Community On Kumo Island Tobelo Subdistrict, North Halmahera Regency

Mangroves are unique plants because they are able to survive in extreme areas with high salinity levels. Mangroves are also often referred to as tidal plants because their growth is influenced by tides. This study uses the quadrant transect line method by determining 3 observation points (stations) taking samples, and determining the condition of mangroves, the calculation of species density, species frequency, species closure, importance value index, and diversity. For environmental variables, several measurements were made, namely temperature, salinity, and type of substrate on Kumo Island. From the results of the study, it is known that mangrove species that have a high density are R.apiculata species and the highest frequency value is in the same species S.alba, while the value of diversity shows a moderate value. The temperature range on Kumo Island is around 29-30 C, as well as the salinity range of 29-30 ppt, and the dominating substrate which is muddy, causes the S.alba species to be found more than other species.Keywords: Kumo Island, Community Structure, MangroveAbstrakMangrove merupakan tumbuhan yang unik dan khas karena mampu bertahan hidup pada daerah yang ekstrim dengan kadar salinitas yang tinggi. Mangrove juga sering disebut dengan tumbuhan pasang surut karena pertumbuhanya dipengaruhi oleh pasang surut .Penelitian ini mengunakan metode line transek kuadran dengan menentukan 3 titik pengamatan (stasiun) pengambilan sempel,dan untuk mengetahui kondisi mangrove maka dilakukan perhitungan kerapatan jenis, frekuensi jenis, penutupan jenis, indeks nilai penting dan keanekaragam. Untuk variabel lingkungan dilakukan beberapa pengukuran yaitu suhu, salinitas dan tipe substrat yang ada di Pulau Kumo. Dari hasil penelitian diketahui jenis mangrove yang memiliki kerapatan tinggi yaitu jenis R.apiculata  dan untuk nilai frekuensi tertingi ada pada jenis S.alba, sedangkan untuk nilai  tutupan ada pada jenis S.alba, untuk keanekaragam menunjukan nilai yang sedang. Kisaran suhu di Pulau Kumo  yaitu sekitar 29-30 C, sama halnya dengan kisaran salinitas yaitu 29-30 ppt dan untuk substrat yang mendominasi yaitu berlumpur,hal ini menyebabpkan jenis S.alba banyak ditemukan dari pada jenis yang lain.Kata kunci: Pulau Kumo, Struktur Komonitas, Mangrov

The 4^4He(e,e′p)(e,e'p) Cross Section at Large Missing Energy

The $(e,e'p)$ reaction on $^{4}{He}$ nuclei was studied in kinematics designed to emphasize effects of nuclear short-range correlations. The measured cross sections display a peak in the kinematical regions where two-nucleon processes are expected to dominate. Theoretical models incorporating short-range correlation effects agree reasonably with the data.Comment: 4 pages LaTeX, using espcrc1.sty and wrapfig.sty (included), two figures. Talk presented by J. Templon at the 15th Int. Conf. on Few-Body Problems in Physics, Groningen, The Netherlands, 22-26 July, 199

Realistic Model of the Nucleon Spectral Function in Few- and Many- Nucleon Systems

By analysing the high momentum features of the nucleon momentum distribution in light and complex nuclei, it is argued that the basic two-nucleon configurations generating the structure of the nucleon Spectral Function at high values of the nucleon momentum and removal energy, can be properly described by a factorised ansatz for the nuclear wave function, which leads to a nucleon Spectral Function in the form of a convolution integral involving the momentum distributions describing the relative and center-of-mass motion of a correlated nucleon-nucleon pair embedded in the medium. The Spectral Functions of $^3He$ and infinite nuclear matter resulting from the convolution formula and from many-body calculations are compared, and a very good agreement in a wide range of values of nucleon momentum and removal energy is found. Applications of the model to the analysis of inclusive and exclusive processes are presented, illustrating those features of the cross section which are sensitive to that part of the Spectral Function which is governed by short-range and tensor nucleon-nucleon correlations.Comment: 40 pages Latex , 16 ps figures available from the above e-mail address or from [email protected]

Special issue on recent advances in lot sizing

Production planning aims to efficiently plan the production activities as well as the acquisition of the raw materials and resources required to transform raw materials into finished products, in order to meet customer demand in the most economical way possible. The decisions to be made include, but are not limited to, production lot sizes, setup decisions, work force levels and sequencing of production runs, while the ultimate aim is to determine the optimal timing and level of production

A computational analysis of lower bounds for big bucket production planning problems

In this paper, we analyze a variety of approaches to obtain lower bounds for multi-level production planning problems with big bucket capacities, i.e., problems in which multiple items compete for the same resources. We give an extensive survey of both known and new methods, and also establish relationships between some of these methods that, to our knowledge, have not been presented before. As will be highlighted, understanding the substructures of difficult problems provide crucial insights on why these problems are hard to solve, and this is addressed by a thorough analysis in the paper. We conclude with computational results on a variety of widely used test sets, and a discussion of future research