47,854 research outputs found
A new gorgonian genus from deep-sea Antarctic waters (Octocorallia, Alcyonacea, Plexauridae)
Mesogligorgia scotiae gen. nov., sp. nov. is
described and illustrated from a colony collected in the
Scotia Sea, 2,201–2,213 m in depth, on the ANDEEP-I
cruise. The new taxon is placed in the family Plexauridae
because of: 1) the presence of a horny axis with a crosschambered central core and numerous loculi, 2) retractile polyps in calyces with distinct spicular components,
and 3) armed polyps with large sclerites with a poorlydeveloped collaret and eight well-developed points. The
irregularly distributed sclerites running along the axis,
into a thick mesogloeal coenenchyme, and the elongated
spindles with irregular ends are the most distinctive
characters of the newly proposed genus
A Multigrid Optimization Algorithm for the Numerical Solution of Quasilinear Variational Inequalities Involving the -Laplacian
In this paper we propose a multigrid optimization algorithm (MG/OPT) for the
numerical solution of a class of quasilinear variational inequalities of the
second kind. This approach is enabled by the fact that the solution of the
variational inequality is given by the minimizer of a nonsmooth energy
functional, involving the -Laplace operator. We propose a Huber
regularization of the functional and a finite element discretization for the
problem. Further, we analyze the regularity of the discretized energy
functional, and we are able to prove that its Jacobian is slantly
differentiable. This regularity property is useful to analyze the convergence
of the MG/OPT algorithm. In fact, we demostrate that the algorithm is globally
convergent by using a mean value theorem for semismooth functions. Finally, we
apply the MG/OPT algorithm to the numerical simulation of the viscoplastic flow
of Bingham, Casson and Herschel-Bulkley fluids in a pipe. Several experiments
are carried out to show the efficiency of the proposed algorithm when solving
this kind of fluid mechanics problems
Transcription-mediated replication hindrance: a major driver of genome instability
Genome replication involves dealing with obstacles that
can result from DNA damage but also from chromatin alterations, topological stress, tightly bound proteins or
non-B DNA structures such as R loops. Experimental evidence reveals that an engaged transcription machinery at
the DNA can either enhance such obstacles or be an obstacle itself. Thus, transcription can become a potentially
hazardous process promoting localized replication fork
hindrance and stress, which would ultimately cause genome instability, a hallmark of cancer cells. Understanding the causes behind transcription–replication conflicts
as well as how the cell resolves them to sustain genome
integrity is the aim of this review
The gastropod-symbiotic sea anemone genus Isosicyonis Carlgren, 1927 (Actiniaria : Actiniidae): a new species from the Weddell Sea (Antarctica) that clarifies the taxonomic position of the genus
A second species of the sea anemone genus Isosicyonis is described and illustrated from 16 specimens collected in the Weddell Sea (Antarctica) on the Polarstern cruises ANT XVII/3, ANT XXI/2 and ANT XXIII/8. Isosicyonis striata n. sp. is easily distinguishable externally from the other species of the genus Isosicyonis alba by its pattern: white longitudinal stripes on the column, oral disc, and tentacles. It is also distinguished by internal features including the retractor muscles, parietobasilar muscles, marginal sphincter muscles, number of mesenteries, and cnidae. The genus Isosycionis is currently only known from the Southern Ocean. Both species of Isosicyonis live in association with a gastropod, with a single sea anemone occupying almost the whole shell of its gastropod host. The description of this new species, and our re-examination of Isosicyonis alba, resolves the controversial higher taxonomic position of the genus, confirming its placement within the Endomyaria
A geometric description of the extreme Khovanov cohomology
We prove that the hypothetical extreme Khovanov cohomology of a link is the cohomology of the independence simplicial complex of its Lando graph. We also provide a family of knots having as many non-trivial extreme Khovanov cohomology modules as desired, that is, examples of H-thick knots which are as far of being H-thin as desired.Ministerio de Economía y CompetitividadFondo Europeo de Desarrollo Regiona
El retorno asistido de Migrantes Centroamericanos en Situación irregular en el Estado de México.
En la presente investigación el tema a trabajar será el retorno asistido de migrantes centroamericanos en situación irregular como objeto de estudio, el cual se delimita al Estado de México como entidad federativa de tránsito de migrantes y la línea de investigación se lleva a cabo dentro de los derechos humanos como rama del derecho internacional público; debido a la importancia del derecho a la libre circulación y residencia como derecho fundamental, reconocido por el Estado mexicano desde la firma y ratificación de los tratados internacionales en materia de derechos humanos, a partir de la reforma constitucional en 2011
New record of the sea anemone Kadosactis antarctica (Carlgren, 1928): re-description of an Antarctic deep-sea sea anemone, and a discussion of its generic and familial placement
Sagartiogeton antarcticus Carlgren, 1928 is an
Antarctic deep-sea species of sea anemone only known
from its holotype. The species has been assigned to the
genera Sagartiogeton and Kadosactis, and is currently
placed within the family Kadosactidae Riemann-Zu¨rneck, 1991. Kadosactis antarctica is re-described based
on 11 specimens collected during the cruise of the R/V
Polarstern ANT XIX/3 (ANDEEP-I) to the Scotia Sea
and off the South Shetland Islands (Antarctica). The
description includes a complete account of cnidae and
photographs. Because the mesogloea is thickened on the
aboral surface on the base of the tentacles, this feature
becomes a generic character of Kadosactis rather than a
differential specific character among the species of the
genus as previously proposed. Furthermore, the known
distribution of the species is enlarged to include the
southern branch of the Scotia Sea
Two new species of Ammothea (Pycnogonida, Ammotheidae) from Antarctic waters
Two new species of the genus Ammothea are
described from Elephant Island and the South Shetlands
Islands, Antarctica. The material was captured during the
Polarstern cruise XXIII/8 to the Antarctic Peninsula area.
The main features of Ammothea pseudospinosa n. sp. are a
proboscis distinctly trilobulated distally with a constriction
at 2/3 of its length and dimorphism between the propodi of
the anterior (first and second) and posterior (third and
fourth) legs, and a trunk: proboscis length ratio of about
1.5. The main features of Ammothea childi n. sp. are a
cylindrical proboscis, longer than trunk length, and adults
with functional chelifores. These species are compared
with their closest congeners from the Southern Ocean:
A. pseudospinosa n. sp. with Ammothea spinosa and
Ammothea allopodes;A. childi n. sp. withAmmothea gigantea,
Ammothea bicorniculata and Ammothea hesperidensis
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