5,123 research outputs found
Discovery of shocked H2 around OH 231.8+4.2
We present K-band integral field observations of the circumstellar envelope
of the evolved star OH 231.8+4.2. Spatial and spectral information were
simultaneously acquired using the Sinfoni integral field unit, with adaptive
optics, on the Very Large Telescope. The observations reveal the discovery of
H2 emission (1) around the centre of the nebula and (2) located in clumps along
the Western side of the Northern lobe, presumably associated with the strong
shocks that stimulate the previously reported H-alpha emission at the same
location. An observed H2 1-0/2-1S(1) line ratio of 8.3+/-1.9 was calculated for
the central field, a value consistent with shock excitation.Comment: 5 pages, 4 figures, accepted for publication in MNRAS Letter
Alternating Hamiltonian cycles in -edge-colored multigraphs
A path (cycle) in a -edge-colored multigraph is alternating if no two
consecutive edges have the same color. The problem of determining the existence
of alternating Hamiltonian paths and cycles in -edge-colored multigraphs is
an -complete problem and it has been studied by several authors.
In Bang-Jensen and Gutin's book "Digraphs: Theory, Algorithms and
Applications", it is devoted one chapter to survey the last results on this
topic. Most results on the existence of alternating Hamiltonian paths and
cycles concern on complete and bipartite complete multigraphs and a few ones on
multigraphs with high monochromatic degrees or regular monochromatic subgraphs.
In this work, we use a different approach imposing local conditions on the
multigraphs and it is worthwhile to notice that the class of multigraphs we
deal with is much larger than, and includes, complete multigraphs, and we
provide a full characterization of this class.
Given a -edge-colored multigraph , we say that is
--closed (resp. --closed)} if for every
monochromatic (resp. non-monochromatic) -path , there
exists an edge between and . In this work we provide the following
characterization: A --closed multigraph has an alternating
Hamiltonian cycle if and only if it is color-connected and it has an
alternating cycle factor.
Furthermore, we construct an infinite family of --closed
graphs, color-connected, with an alternating cycle factor, and with no
alternating Hamiltonian cycle.Comment: 15 pages, 20 figure
Chemical Plant Defense Against Herbivores
Herbivores can damage plant productivity and fitness because plants have improved defense mechanisms such as physical barriers, association with other organisms such as ants, and chemical defense. In that, separate plant species produce different chemical molecules. Chemical compounds involved in plant defense can act in several facts: decreased palatability, like a poison, such as a stunner, and increased gene defense expression, among others. In this chapter, we approach several examples of chemical molecules produced by plants to defend themselves, including biochemical metabolic pathways, as well as ecological and evolutive implications
De las políticas públicas implementadas a partir del estado de cosas inconstitucional (T-388/13): crisis en el sistema penitenciario y carcelario, violación grave y sistemática del derecho a la salud
Artículo de investigaciónEl presente tema de investigación, ha sido por varios años un problema para el Estado Colombiano, ya que es uno de los países donde se incrementa la vulneración de los derechos fundamentales de las personas que se encuentran privadas de la libertad.
En Colombia, los centros penitenciarios y carcelarios no cuentan con el personal médico suficiente, con los implementos adecuados, tienen deficiencia en el suministro de medicamentos, y trabajan en condiciones insalubres y sin higiene. Con el pasar de los años la salud se vuelve más precaria, es más difícil acceder a las mínimas atenciones; ahora, en los centros penitenciarios es peor, pues se habla de una población condenada, marginada y que se encuentra abandonada por el Estado, cada vez aumentan las tutelas interpuestas ante la Corte Constitucional por las diferentes personas que ven vulnerado su derecho fundamental a la Salud, por ello, se observa que la vulneración de los derechos fundamentales de los reclusos crece frecuentemente sin encontrar solución alguna.INTRODUCCIÓN. 1. Conceptos y antecedentes del Derecho Fundamental de la Salud, Estado de Cosas Inconstitucional y Políticas Públicas. 2. Políticas públicas implementadas por las Entidades Públicas para la protección del derecho a la salud en personas privadas de la libertad. 3. Informes remitidos de seguimiento y cumplimiento de la orden interpuesta por la Corte a las Entidades Públicas. 4. Comentarios con base a informes de cumplimiento y seguimiento. 5. Conclusiones. 6. ReferenciasPregradoAbogad
Tripod-shaped penta (p-phenylene)s for the functionalization of silicon surfaces
In order to obtain nanostructured thin films to be used in biosensor devices, several chemical functionalization methods have been developed, such as Click chemistry or Suzuki carbon-carbon coupling reactions on surfaces.1
With the aim to control the orientation and spacing between grafted functional groups on a surface, tripodal oligo (p-phenylene)s have become the ideal anisotropic adsorbates due to their shape-persistent and self-standing characteristics.2
Here we report the synthesis and characterization of several tripod-shaped oligo(p-phenylene)s molecules with legs composed of five phenylene units, compounds 1, 2 and 3. In these structures, each leg is end-capped with an NH-Boc, NH2 and N3 group, respectively. The functional arm contains an acetylene group. The presented synthesis has as key step the Pd-catalyzed Suzuki cross-coupling reaction. In particular, a iodine derivative from the silicon core molecule reacts with the appropriate tetra(p-phenylene) boron derivative, thus generating the final tripod-shaped structure. The azide end-capped leg in 3 is specifically designed for its covalent incorporation on alkynyl terminated silicon surfaces by an easy and reproducible way. As a preliminary study, we present the alkynyl-functionalized silicon wafers nanostructuration with tripod 3 through the cooper catalyzed alkyne-azide cycloaddition (CuAAC) click reaction.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
Binarity in Cool Asymptotic Giant Branch Stars: A Galex Search for Ultraviolet Excesse
The search for binarity in AGB stars is of critical importance for our
understanding of how planetary nebulae acquire the dazzling variety of
aspherical shapes which characterises this class. However, detecting binary
companions in such stars has been severely hampered due to their extreme
luminosities and pulsations. We have carried out a small imaging survey of AGB
stars in ultraviolet light (using GALEX) where these cool objects are very
faint, in order to search for hotter companions. We report the discovery of
significant far-ultraviolet excesses towards nine of these stars. The
far-ultraviolet excess most likely results either directly from the presence of
a hot binary companion, or indirectly from a hot accretion disk around the
companion.Comment: revised for Astrophysical Journa
Efecto de los Edulcorantes GE y Sucralosa en la respuesta inmunológica Pro-Inflamatoria
El sistema inmunológico es uno de los mecanismos biológicos más importantes que permite mantener la integridad estructural y funcional del organismo, conservando así la homeostasis. Las citocinas son proteínas fundamentales para la respuesta inmunológica, actúan comunicando a las células del sistema inmunitario entre sí. Estas proteínas son de gran interés, debido a que las Enfermedades Crónicas No Transmisibles (ECNT) se caracterizan por una respuesta inflamatoria crónica de bajo grado, causada por la producción anormal de este tipo de moléculas
Investigación acerca de la enseñanza del límite en el marco de teoría de las funciones semióticas
La enseñanza-aprendizaje de los conceptos elementales del Análisis matemático en el nivel del Bachillerato, constituye uno de los puntos de investigación en Didáctica de las Matemáticas más relevantes en la actualidad. Desde marcos teóricos diferentes como la ingeniería didáctica, teoría de obstáculos, la teoría antropológica o el APOS, se han realizado investigaciones sobre la enseñanza-aprendizaje del límite de una función en los niveles de enseñanza de Bachillerato y Universitaria. En este trabajo se presenta una propuesta de investigación, en la que se aplica la teoría de las cuestiones semióticas (TFS), mediante la cual se busca describir, explicar e identificar factores condicionantes de la enseñanza-aprendizaje del límite de una función en un contexto institucional fijado
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