13,606 research outputs found
Transcriptome of the deep-sea black scabbardfish, Aphanopus carbo (Perciformes: Trichiuridae) : tissue-specific expression patterns and candidate genes associated to depth adaptation
Deep-sea fishes provide a unique opportunity to study the physiology and evolutionary adaptation to extreme environments. We carried out a high throughput sequencing analysis on a 454 GS-FLX titanium plate using unnormalized cDNA libraries from six tissues of A. carbo. Assemblage and annotations were performed by Newbler and InterPro/Pfam analyses, respectively. The assembly of 544,491 high quality reads provided 8,319 contigs, 55.6% of which retrieved blast hits against the NCBI nonredundant database or were annotated with ESTscan. Comparison of functional genes at both the protein sequences and protein stability levels, associated with adaptations to depth, revealed similarities between A. carbo and other bathypelagic fishes. A selection of putative genes was standardized to evaluate the correlation between number of contigs and their normalized expression, as determined by qPCR amplification. The screening of the libraries contributed to the identification of new EST simple-sequence repeats (SSRs) and to the design of primer pairs suitable for population genetic studies as well as for tagging and mapping of genes. The characterization of the deep-sea fish A. carbo first transcriptome is expected to provide abundant resources for genetic, evolutionary, and ecological studies of this species and the basis for further investigation of depth-related adaptation processes in fishes.Publisher PDFPeer reviewe
Klein tunneling in carbon nanostructures: a free particle dynamics in disguise
The absence of backscattering in metallic nanotubes as well as perfect Klein
tunneling in potential barriers in graphene are the prominent electronic
characteristics of carbon nanostructures. We show that the phenomena can be
explained by a peculiar supersymmetry generated by a first order Hamiltonian
and zero order supercharge operators. Like the supersymmetry associated with
second order reflectionless finite-gap systems, it relates here the low-energy
behavior of the charge carriers with the free particle dynamics.Comment: 4 pages, 1 fig., typos correcte
Focusing of opinions in the Deffuant model: First impression counts
The paper treats opinion dynamics of an unequal distribution as the initial
opinion distribution. Simulated is the Deffuant model on a directed
Barabasi-Albert network with discrete opinions and several subjects. Noticed is
a focusing of the the resulting opinion distribution during the simulation
towards the average value of the initial opinion distribution. A small change
of the focusing is seen. A dependency of this change on the number of subjects
and opinions is detected and indicates the change as a consequence of
discretization the opinions. Hereby the average value of the initial opinion
distribution can be identified as the guide of opinion forming.Comment: 8 pages including 5 figures, for Int. J. Mod. Phys.
Linear Invariant Systems Theory for Signal Enhancement
This paper discusses a linear time invariant (LTI) systems approach to signal enhancement via projective subspace techniques. It provides closed form expressions for the frequency response of data adaptive finite impulse response eigenfilters. An illustrative example using speech enhancement is also presented.Este artigo apresenta a aplicação da teoria de sistemas lineares invariantes no tempo (LTI) na análise de técnicas de sub-espaço. A resposta em frequência dos filtros resultantes da decomposição em valores singulares é obtida aplicando as propriedades dos sistemas LTI
Phase diagrams of Janus fluids with up-down constrained orientations
A class of binary mixtures of Janus fluids formed by colloidal spheres with
the hydrophobic hemispheres constrained to point either up or down are studied
by means of Gibbs ensemble Monte Carlo simulations and simple analytical
approximations. These fluids can be experimentally realized by the application
of an external static electrical field. The gas-liquid and demixing phase
transitions in five specific models with different patch-patch affinities are
analyzed. It is found that a gas-liquid transition is present in all the
models, even if only one of the four possible patch-patch interactions is
attractive. Moreover, provided the attraction between like particles is
stronger than between unlike particles, the system demixes into two subsystems
with different composition at sufficiently low temperatures and high densities.Comment: 10 pages, 6 figure
How veganism impacts tourists attitudes toward tourism destinations: An empirical study
The purpose of this study is to examine the structural relationships of the veganism motivations on the vegan tourist attitudes towards the tourist destination offers, and consequently on satisfaction, intention to revisit and recommend. Food and tourism are intimately related in many ways, and a growing trend towards vegan food consumption and lifestyle could pose a challenge for the tourism sector. This paper presents the conceptual framework and research design of the study. Multivariate analysis techniques, such as reliability analysis, factor analysis, and structural equation modelling will be used to validate the proposed measurement and structural model. This study intends to contribute with new insights on the vegan tourist and how vegan tourist destinations can improve this type of tourist experience in this growing segment.info:eu-repo/semantics/publishedVersio
Teor de vitamina C, em citrinos cultivados no Algarve.
O crescimento, a maturação e a qualidade dos citrinos, através da determinação das características físico-químicas, têm sido amplamente estudadas em função de vários fac-tores, como sejam a variedade, o porta-enxertos e as condições edafo-climáticas e eco-lógicas em que são cultivados (Reuther et al., 1969; Rouse, 1989). O valor nutritivo dos citrinos é, em parte, devido ao elevado teor de ácido ascórbico presente no sumo. Este facto torna a determinação deste parâmetro muito importante não só nos frutos frescos como nos utilizados na indústria. Num futuro próximo, o teor de vitamina C no fruto poderá vir a ser considerado como um importante parâmetro de qualidade da fruta. O teor do ácido ascórbico depende de vários factortes, nomeadamente, orientação e insolação do pomar, maturação, porta-enxerto, solo e fertilização. Em solução aquosa,o ácido ascórbico oxida com relativa facilidade, o que conduz à oscilação dos seus teores no fruto. A conservação deste ácido no sumo depende das condições de laboração, do tempo e da temperatura de armazenamento, do conteúdo de oxigénio dissolvido, e do material de empacotamento, das caracterísicas intrínsecas do próprio sumo, da luz, presença de metais pesados, enzimas, etc. (Fernández, 1995). Neste trabalho, estudou-se o a evolução do índice de maturação e do teor de vitamina C em pomares de 'Newhall' e 'Valencia Late', com diferentes condições edafoclimáticas.info:eu-repo/semantics/publishedVersio
3D Simulations of Relativistic Precessing Jets Probing the Structure of Superluminal Sources
We present the results of a three-dimensional, relativistic, hydrodynamic
simulation of a precessing jet into which a compact blob of matter is injected.
A comparison of synthetic radio maps computed from the hydrodynamic model,
taking into account the appropriate light travel time delays, with those
obtained from observations of actual superluminal sources shows that the
variability of the jet emission is the result of a complex combination of phase
motions, viewing angle selection effects, and non-linear interactions between
perturbations and the underlying jet and/or the external medium. These results
question the hydrodynamic properties inferred from observed apparent motions
and radio structures, and reveal that shock-in-jet models may be overly
simplistic.Comment: Accepted for publication in ApJL. 4 pages, 5 figures (4 in color
Optimality of Gaussian Attacks in Continuous Variable Quantum Cryptography
We analyze the asymptotic security of the family of Gaussian modulated
Quantum Key Distribution protocols for Continuous Variables systems. We prove
that the Gaussian unitary attack is optimal for all the considered bounds on
the key rate when the first and second momenta of the canonical variables
involved are known by the honest parties.Comment: See also R. Garcia-Patron and N. Cerf, quant-ph/060803
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