Length-weight relationships of coral reef fishes from the Alacran Reef, Yucatan, Mexico

Length-weight relationships were computed for 42 species of coral reef fishes from 14 families from the Alacran Reef (Yucatan, Mexico). A total of 1 892 individuals was used for this purpose. The fish species were caught by different fishing techniques such as fishhooks, harpoons, gill and trawl nets. The sampling period was from March 1998 to January 2000

Disentangling phase transitions and critical points in the proton-neutron interacting boson model by catastrophe theory

We introduce the basic concepts of catastrophe theory needed to derive analytically the phase diagram of the proton-neutron interacting boson model (IBM-2). Previous studies [1-3] were based on numerical solutions. We here explain the whole IBM-2 phase diagram including the precise order of the phase transitions in terms of the cusp catastrophe. © 2014 The Authors.This work was partially supported by the Spanish Ministerio de Econom´ıa y Competitividad and the European regional development fund (FEDER) under Project Nos. FIS2011-28738-C02-01, FIS2011-28738-C02-02, FIS2012-34479, and by Junta de Andaluc´ıa under Project Nos. FQM160, P11-FQM-7632 and FQM318, as well as by Spanish Consolider-Ingenio 2010 (CPANCSD2007-00042).Peer Reviewe

D'atri spaces of type k and related classes of geometries concerning jacobi operators

In this article we continue the study of the geometry of $k$-D'Atri spaces, $$ $\leq n-1$ ($n$ denotes the dimension of the manifold)$,$ began by the second author. It is known that $k$-D'Atri spaces, $k\geq 1,$ are related to properties of Jacobi operators $R_{v}$ along geodesics, since she has shown that ${\operatorname{tr}}R_{v}$, ${\operatorname{tr}}R_{v}^{2}$ are invariant under the geodesic flow for any unit tangent vector $v$. Here, assuming that the Riemannian manifold is a D'Atri space, we prove in our main result that ${\operatorname{tr}}R_{v}^{3}$ is also invariant under the geodesic flow if $k\geq 3$. In addition, other properties of Jacobi operators related to the Ledger conditions are obtained and they are used to give applications to Iwasawa type spaces. In the class of D'Atri spaces of Iwasawa type, we show two different characterizations of the symmetric spaces of noncompact type: they are exactly the $\frak{C}$-spaces and on the other hand they are $k$ -D'Atri spaces for some $k\geq 3.$ In the last case, they are $k$-D'Atri for all $k=1,...,n-1$ as well. In particular, Damek-Ricci spaces that are $k$-D'Atri for some $k\geq 3$ are symmetric. Finally, we characterize $k$-D'Atri spaces for all $k=1,...,n-1$ as the $\frak{SC}$-spaces (geodesic symmetries preserve the principal curvatures of small geodesic spheres). Moreover, applying this result in the case of 4% -dimensional homogeneous spaces we prove that the properties of being a D'Atri (1-D'Atri) space, or a 3-D'Atri space, are equivalent to the property of being a $k$-D'Atri space for all $k=1,2,3$.Comment: 19 pages. This paper substitute the previous one where one Theorem has been deleted and one section has been adde

Decoherence due to an excited-state quantum phase transition in a two-level boson model

10 págs.; 8 figs.; 2 tabs.; PACS number s : 03.65.Yz, 05.70.Fh, 64.70.TgThe decoherence induced on a single qubit by its interaction with the environment is studied. The environment is modeled as a scalar two-level boson system that can go through either first-order or continuous-excited-state quantum phase transitions, depending on the values of the control parameters. A mean-field method based on the Tamm-Damkoff approximation is worked out in order to understand the observed behavior of the decoherence. Only the continuous-excited-state phase transition produces a noticeable effect in the decoherence of the qubit. This is maximal when the system-environment coupling brings the environment to the critical point for the continuous phase transition. In this situation, the decoherence factor (or the fidelity) goes to zero with a finite-size scaling power law. © 2009 The American Physical Society.This work has been partially supported by the Spanish Ministerio de Educación y Ciencia and by the European regional development fund FEDER under Projects No. FIS2008-04189, No. FIS2006-12783-C03-01, No. FPA2006- 13807-C02-02, and No. FPA2007-63074, by CPAN-Ingenio, by Comunidad de Madrid under Project No. 200650M012, CSIC, and by Junta de Analucía under Projects No. FQM160, No. FQM318, No. P05-FQM437, and No. P07- FQM-02962. A.R. is supported by the Spanish program “Juan de la Cierva” and P. P-F. is supported by a FPU grant of the Spanish Ministerio de Educación y Ciencia.Peer Reviewe

Continuous unitary transformations in two-level boson systems

17 págs.; 16 figs.; 1 tab.; 3 apéndices ; PACS number(s): 21.60.Fw, 21.10.Re, 05.10.Cc, 75.40.CxTwo-level boson systems displaying a quantum phase transition from a spherical (symmetric) to a deformed (broken) phase are studied. A formalism to diagonalize Hamiltonians with O(2L+1) symmetry for large number of bosons is worked out. Analytical results beyond the simple mean-field treatment are deduced by using the continuous unitary transformations technique. In this scheme, a 1/N expansion for different observables is proposed and allows one to compute the finite-size scaling exponents at the critical point. Analytical and numerical results are compared and reveal the power of the present approach to compute the finite-size corrections in such a context. © 2005 The American Physical Society.S. Dusuel gratefully acknowledges financial support of the DFG in SP1073. This work has been partially supported by the Spanish DGI under projects FIS2005-01105, BFM2003-05316-C02-02, BFM2003-05316, and FPA2003-05958.Peer Reviewe

Pressure-induced metal-insulator transition in MgV_2O_4

On the basis of experimental thermoelectric power results and ab initio calculations, we propose that a metal-insulator transition takes place at high pressure (approximately 6 GPa) in MgV_2O_4.Comment: 2 pages, 3 figures, accepted in Physica B (Strongly Correlated Electron Systems '07

Plan de comunicaciones para la campaña de prevención contra la sigatoka negra del plátano y banano en Urabá.

Banano- Musa acuminata - Musa paradisiacaPlátano-Musa sapientu

NOD2 Modulates Serotonin Transporter and Interacts with TLR2 and TLR4 in Intestinal Epithelial Cells

Background/Aims: Serotonin (5-HT) is a chief modulator of intestinal activity. The effects of 5-HT depend on its extracellular availability, which is mainly controlled by serotonin transporter (SERT), expressed in enterocytes. On the other hand, innate immunity, mediated by Toll-like receptors (TLRs) and nucleotide oligomerization domain (NOD)-like receptors (NLRs), is known to control intestinal microbiota and maintain intestinal homeostasis. The dysregulation of the intestinal serotonergic system and innate immunity has been observed in in ammatory bowel diseases (IBD), the incidence of which has severely increased all over the world. The aim of the present study, therefore, was to analyze the effect of NOD2 on intestinal SERT activity and expression, as well as to study the crosstalk of NOD2 with TLR2 and TLR4. Methods: Intestinal epithelial cell line Caco-2/TC7 was used to analyze SERT activity and SERT, NOD2, TLR2 and TLR4 molecular expression by real-time PCR and western blotting. Moreover, intestinal tract (ileum and colon) from mice de cient in TLR2, TLR4 or TLR2/4 receptors was used to test the interdependence of NOD2 with these TLR receptors. Results: NOD2 activation inhibits SERT activity in Caco-2/TC7 cells, mainly due to the decrement of SERT molecular expression, with RIP2/RICK being the intracellular pathway involved in this effect. This inhibitory effect on SERT would yield an increment of extracellular 5-HT availability. In this sense, 5-HT strongly inhibits NOD2 expression. In addition, NOD2 showed greater interdependence with TLR2 than with TLR4. Indeed, NOD2 expression signi cantly increased in both cells treated with TLR2 agonists and the intestinal tract of Tlr2-/- mice. Conclusions: It may be inferred from our data that NOD2 could play a role in intestinal pathophysiology not only through its inherent innate immune role but also due to its interaction with other receptors as TLR2 and the modulation of the intestinal serotonergic system decreasing SERT activity and expression

Growth and mortality of Ctenochaetus striatus, Stegastes nigricans and Sargocentron microstoma in Tiahura Reef, Moorea Island, French Polynesia

Growth parameters and mortality rates were estimated from length-frequency data sampled in 1982, using the FiSAT software, for three coral reef fish species, the surgeon fish (Ctenochaetus striatus), the damselfish (Stegastes nigricans) and the squirrel fish (Sargocentron microstoma) in Tiahura Reef, Moorea Island, French Polynesia