Stabilization of solitons of the multidimensional nonlinear Schrodinger equation: Matter-wave breathers

We demonstrate that stabilization of solitons of the multidimensional Schrodinger equation with a cubic nonlinearity may be achieved by a suitable periodic control of the nonlinear term. The effect of this control is to stabilize the unstable solitary waves which belong to the frontier between expanding and collapsing solutions and to provide an oscillating solitonic structure, some sort of breather-type solution. We obtain precise conditions on the control parameters to achieve the stabilization and compare our results with accurate numerical simulations of the nonlinear Schrodinger equation. Because of the application of these ideas to matter waves these solutions are some sort of matter breathers

Origin of the peculiar eccentricity distribution of the inner cold Kuiper belt

Dawson and Murray-Clay (2012) pointed out that the inner part of the cold population in the Kuiper belt (that with semi major axis a<43.5 AU) has orbital eccentricities significantly smaller than the limit imposed by stability constraints. Here, we confirm their result by looking at the orbital distribution and stability properties in proper element space. We show that the observed distribution could have been produced by the slow sweeping of the 4/7 mean motion resonance with Neptune that accompanied the end of Neptune's migration process. The orbital distribution of the hot Kuiper belt is not significantly affected in this process, for the reasons discussed in the main text. Therefore, the peculiar eccentricity distribution of the inner cold population can not be unequivocally interpreted as evidence that the cold population formed in-situ and was only moderately excited in eccentricity; it can simply be the signature of Neptune's radial motion, starting from a moderately eccentric orbit. We discuss how this agrees with a scenario of giant planet evolution following a dynamical instability and, possibly, with the radial transport of the cold population.Comment: in press in Icaru

Durabilidad del hormigón. programa de investigación del IETcc

[ES] El comportamiento de los morteros y hormigones sometidos a la acción de ambientes agresivos naturales (atmósferas; terrenos; aguas —puras, con componentes disueltos, residuales, de mar—, etc.) ha sido objeto.de numerosos trabajos como consecuencia de la gran cantidad de obras construidas a base de hormigón, en masa y armado, las cuales han sufrido lesiones de consideración que, en determinados casos, supusieron fracasos resonantes como consecuencia de la descomposición experimentada; de aquí, que sea un tema que ha preocupado y sigue interesando a los profesionales, no sólo desde un punto de vista tecnológico o constructivo sino científico, para conocer las causas que producen la destrucción de dichas^ obras y poder tomar, en su caso, las medidas oportunas.Peer reviewe

Stable propagation of pulsed beams in Kerr focusing media with modulated dispersion

We propose the modulation of dispersion to prevent collapse of planar pulsed beams which propagate in Kerr-type self-focusing optical media. As a result, we find a new type of two-dimensional spatio-temporal solitons stabilized by dispersion management. We have studied the existence and properties of these solitary waves both analytically and numerically. We show that the adequate choice of the modulation parameters optimizes the stabilization of the pulse.Comment: 3 pages, 3 figures, submitted to Optics Letter

Study of Long Weight Relation of Scylla Serrata in Mangrove Forest Around the Wet Laboratory FPIK Eeast Likupang District North Minahasa

Kepiting bakau (Scylla serrata) adalah binatang anggota crustasea berkaki sepuluh dari infraordo Brachura, yang dikenal mempunyai ekor yang sangat pendek (dalam bahasa Yunani : brachy = pendek, ura = ekor). Kepiting bakau adalah salah satu biota perairan yang bernilai ekonomis penting dan kehidupannya sangat dipengaruhi oleh keberadaan hutan mangrove. Adapun tujuan dari penelitian ini yaitu untuk mengidentifikasi dan menganalisis hubungan panjang berat berserta pola pertumbuhan dari kepiting bakau (Scylla serrata). Pengambilan sampel diperoleh dengan melakukan kegiatan penangkapan menggunakan alat tangkap yaitu bubu (chang). Berdasarkan hasil penelitian yang dilakukan di Daerah Hutan Mangrove sekitar Laboratorium Basah Fakultas Perikanan dan Ilmu Kelautan, Likupang Timur pada bulan Agustus – September 2017. Kepiting bakau (Scylla serrata) yang di dapat selama melalukan penelitian diperoleh sebanyak 32 individu

Struktur Komunitas Teripang (Holothuroidea) Di Kawasan Pantai Desa Ondong Kecamatan Siau Barat Kabupaten Siau Tagulandang Biaro1

Sea cucumbers is a group of marine invertebrates belonging to class holothuroidea. At this time, the hunting for sea cucumber is not just targetted on the expensive species, but also the cheap one. The exploitation pressure has caused population decline which can cause changes in their community structure. This research was aimed to understand the types of sea cucumber, analyze the structure of the community sea cucumber which includes the density of individuals, diversity index, the dominance index, interspecific and the dispersion pattern. Sample collection was done at night at the lowest tide in December, 2013. Based on the research activities in the coastal areas of Ondong, west Siau district, Siau-Tagulandang-Biaro regency, 7 species of holothuroidea were found : Holothuria atra, Holothuria leucospilota, Actinopyga echinites, Actinopyga lecanora, Bohadschia argus, Bohadschia marmorata and bohadschia vitiensis, respectively with mean individual density of 0.797 ind/m2, diversity index (H' = 1.718), equity index or harmony (e = 0. 883), dominance index (C = 0.218), interspecific association between 7 species forming 5 pairs of positive associations and 16 pairs of negative association andrandomdistribution

Community Structure of Sea Cucumber (Holothuroidea) in the Coastal Area of the Island of Jailolo Subdistrict Nyaregilaguramangofa South Halmahera Regency West of North Maluku

Sea cucumbers (Holothuroidea) are a group of marine invertebrate animals of the class Holothuroidea (phylum Echinodermata). At present, hunting of sea cucumbers is not only targeted at species of high economic value, but also of low economic value. The pressure of exploitation has led to a decline in the population that can cause changes in the structure of the community. The purpose of this research is to understand the type of sea cucumber, analyze the structure of sea cucumber which includes individual density, diversity index, domination index, inter species association and dispersion pattern. Sampling was conducted at night during the lowest tide in April 2016. Based on the results of research conducted in the coastal area of Nyaregilaguramangofa Island, South Jailolo district, West Halmahera Regency, North Maluku. Species of sea cucumbers found in the study sites were 6 species of sea cucumber: Holothuria atra, Holothuria hilla, Holothuria scabra, Bohadschia marmorata, Bohadschia vitiensis and Ophedesoma grisea, each with an average individual density of 0.029 ind/m2, the diversity index (H \u27= 1,495), the fairness index (e = 0.834), the dominance index (C = 0.260), the association between the six species forming 4 pairs of positive associations and 11 pairs of negative associations and the entire population has a randomly distributed pattern