9,440 research outputs found
Cerberus is a feedback inhibitor of Nodal asymmetric signaling in the chick embryo
The TGF-beta-related molecule Nodal plays an essential and conserved role in left-right patterning of the vertebrate embryo. Previous reports have shown that the zebrafish and mouse Cerberus-related proteins Charon and Cerberus-like-2 (Cerl-2), respectively, act in the node region to prevent the Nodal signal from crossing to the right side, whereas chick Cerberus (cCer) has an unclear function in the left-side mesoderm. In this study, we investigate the transcriptional regulation and function of cCer in left-right development. By analyzing the enhancer activity of cCer 5' genomic sequences in electroporated chick embryos, we identified a cCer left-side enhancer that contains two FoxH1 and one SMAD binding site. We show that these Nodal-responsive elements are necessary and sufficient for the activation of transcription in the left-side mesoderm. In transgenic mouse embryos, cCer regulatory sequences behave as in chick embryos, suggesting that the cis-regulatory sequences of Cerberus-related genes have diverged during vertebrate evolution. Moreover, our findings from cCer overexpression and knockdown experiments indicate that cCer is a negative-feedback regulator of Nodal asymmetric signaling. We propose that cCer and mouse Cerl-2 have evolved distinct regulatory mechanisms but retained a conserved function in left-right development, which is to restrict Nodal activity to the left side of the embryo.info:eu-repo/semantics/publishedVersio
Amphibia, Anura, Pipidae, <i>Pipa pipa,/i>: Distribution extension, new state record and geographic distribution map
Tunable asymmetric magnetoimpedance effect in ferromagnetic NiFe/Cu/Co films
We investigate the magnetization dynamics through the magnetoimpedance effect
in ferromagnetic NiFe/Cu/Co films. We observe that the magnetoimpedance
response is dependent on the thickness of the non-magnetic Cu spacer material,
a fact associated to the kind of the magnetic interaction between the
ferromagnetic layers. Thus, we present an experimental study on asymmetric
magnetoimpedance in ferromagnetic films with biphase magnetic behavior and
explore the possibility of tuning the linear region of the magnetoimpedance
curves around zero magnetic field by varying the thickness of the non-magnetic
spacer material, and probe current frequency. We discuss the experimental
magnetoimpedance results in terms of the different mechanisms governing the
magnetization dynamics at distinct frequency ranges, quasi-static magnetic
properties, thickness of the non-magnetic spacer material, and the kind of the
magnetic interaction between the ferromagnetic layers. The results place
ferromagnetic films with biphase magnetic behavior exhibiting asymmetric
magnetoimpedance effect as a very attractive candidate for application as probe
element in the development of auto-biased linear magnetic field sensors.Comment: 5 figure
Spreading gossip in social networks
We study a simple model of information propagation in social networks, where
two quantities are introduced: the spread factor, which measures the average
maximal fraction of neighbors of a given node that interchange information
among each other, and the spreading time needed for the information to reach
such fraction of nodes. When the information refers to a particular node at
which both quantities are measured, the model can be taken as a model for
gossip propagation. In this context, we apply the model to real empirical
networks of social acquaintances and compare the underlying spreading dynamics
with different types of scale-free and small-world networks. We find that the
number of friendship connections strongly influences the probability of being
gossiped. Finally, we discuss how the spread factor is able to be applied to
other situations.Comment: 10 pages, 16 figures, Revtex; Virt.J. of Biol. Phys., Oct.1 200
Impacto potencial das mudanças climáticas sobre as doenças da mandioca no Brasil.
Doenças causadas por fungos e oomicetos; Doenças causadas por bactĂ©rias; Doenças causadas por vĂrus
Multipartite entanglement sudden death and birth in randomized hypergraph states
We introduce and analyze the entanglement properties of randomized hypergraph
states, as an extended notion of the randomization procedure in the quantum
logic gates for the usual graph states, recently proposed in the literature.
The probabilities of applying imperfect generalized controlled- gates
simulate the noisy operations over the qubits. We obtain entanglement measures
as negativity, concurrence, and genuine multiparticle negativity, and show that
entanglement exhibits a non-monotonic behavior in terms of the randomness
parameters, which is a consequence of the non-uniformity of the associated
hypergraphs, reinforcing the claim that the entanglement of randomized graph
states is monotonic since they are related to -uniform hypergraphs.
Moreover, we observed the phenomena of entanglement sudden death and
entanglement sudden birth in RH states. This work comes to unveil a connection
between the non-uniformity of hypergraphs and loss of entanglement.Comment: 6 pages, 5 figures. Submitted for publication. Comments are welcom
- …