447 research outputs found
Agent Based Models of Language Competition: Macroscopic descriptions and Order-Disorder transitions
We investigate the dynamics of two agent based models of language
competition. In the first model, each individual can be in one of two possible
states, either using language or language , while the second model
incorporates a third state XY, representing individuals that use both languages
(bilinguals). We analyze the models on complex networks and two-dimensional
square lattices by analytical and numerical methods, and show that they exhibit
a transition from one-language dominance to language coexistence. We find that
the coexistence of languages is more difficult to maintain in the Bilinguals
model, where the presence of bilinguals in use facilitates the ultimate
dominance of one of the two languages. A stability analysis reveals that the
coexistence is more unlikely to happen in poorly-connected than in fully
connected networks, and that the dominance of only one language is enhanced as
the connectivity decreases. This dominance effect is even stronger in a
two-dimensional space, where domain coarsening tends to drive the system
towards language consensus.Comment: 30 pages, 11 figure
Analytical Solution of the Voter Model on Disordered Networks
We present a mathematical description of the voter model dynamics on
heterogeneous networks. When the average degree of the graph is
the system reaches complete order exponentially fast. For , a finite
system falls, before it fully orders, in a quasistationary state in which the
average density of active links (links between opposite-state nodes) in
surviving runs is constant and equal to , while an
infinite large system stays ad infinitum in a partially ordered stationary
active state. The mean life time of the quasistationary state is proportional
to the mean time to reach the fully ordered state , which scales as , where is the number of nodes of the
network, and is the second moment of the degree distribution. We find
good agreement between these analytical results and numerical simulations on
random networks with various degree distributions.Comment: 20 pages, 8 figure
Understanding contribution of microstructure to fracture behaviour of sintered steels
Proceedings of: Euro PM2014 Congress & Exhibition, Salzburg, Austria, 21-24 September 2014.This paper was the winner of the EPMA PM Structural Parts Keynote Award made at Euro PM 2014Microstructural features of sintered steels, which comprise both phases and porosity, strongly condition the mechanical behaviour of the material under service conditions. Many research activities have dealt with this relationship since better understanding of the microstructure&-property correlation is the key of improvement of current powder metallurgy (PM) steels. Up to now, fractographic investigation after testing has been successfully applied for this purpose and, more recently, the in situ analysis of crack evolution through the microstructure as well as some advanced computer assisted tools. However, there is still a lack of information about local mechanical behaviour and strain distributions at the microscale in relation to the local microstructure of these steels, i.e. which phases in heterogeneous PM microstructures contribute to localisation of plastic deformation or which phases can impede crack propagation during loading. In the present work, these questions are addressed through the combination of three techniques: (i) in situ tensile testing (performed in the SEM) to monitor crack initiation and propagation; (ii) digital image correlation technique to trace the progress of local strain distributions during loading; (iii) fractographic examination of the loaded samples. Three PM steels, all obtained from commercially available powders but presenting different microstructures, are examined: a ferritic-pearlitic Fe-C steel, a bainitic prealloyed Fe-Mo-C steel and a diffusion alloyed Fe-Ni-Cu-Mo-C steel, with more heterogeneous microstructure (ferrite, pearlite, upper and lower bainite, martensite and Ni rich austenite).The authors wish to thank to Höganäs AB for providing all the raw materials to develop this work.Publicad
Consensus and ordering in language dynamics
We consider two social consensus models, the AB-model and the Naming Game
restricted to two conventions, which describe a population of interacting
agents that can be in either of two equivalent states (A or B) or in a third
mixed (AB) state. Proposed in the context of language competition and
emergence, the AB state was associated with bilingualism and synonymy
respectively. We show that the two models are equivalent in the mean field
approximation, though the differences at the microscopic level have non-trivial
consequences. To point them out, we investigate an extension of these dynamics
in which confidence/trust is considered, focusing on the case of an underlying
fully connected graph, and we show that the consensus-polarization phase
transition taking place in the Naming Game is not observed in the AB model. We
then consider the interface motion in regular lattices. Qualitatively, both
models show the same behavior: a diffusive interface motion in a
one-dimensional lattice, and a curvature driven dynamics with diffusing
stripe-like metastable states in a two-dimensional one. However, in comparison
to the Naming Game, the AB-model dynamics is shown to slow down the diffusion
of such configurations.Comment: 7 pages, 6 figure
Algebraic coarsening in voter models with intermediate states
The introduction of intermediate states in the dynamics of the voter model
modifies the ordering process and restores an effective surface tension. The
logarithmic coarsening of the conventional voter model in two dimensions is
eliminated in favour of an algebraic decay of the density of interfaces with
time, compatible with Model A dynamics at low temperatures. This phenomenon is
addressed by deriving Langevin equations for the dynamics of appropriately
defined continuous fields. These equations are analyzed using field theoretical
arguments and by means of a recently proposed numerical technique for the
integration of stochastic equations with multiplicative noise. We find good
agreement with lattice simulations of the microscopic model.Comment: 11 pages, 5 figures; minor typos correcte
Broad lifetime distributions for ordering dynamics in complex networks
We search for conditions under which a characteristic time scale for ordering
dynamics towards either of two absorbing states in a finite complex network of
interactions does not exist. With this aim, we study random networks and
networks with mesoscale community structure built up from randomly connected
cliques. We find that large heterogeneity at the mesoscale level of the network
appears to be a sufficient mechanism for the absence of a characteristic time
for the dynamics. Such heterogeneity results in dynamical metastable states
that survive at any time scale.Comment: 8 pages, 12 figure
Analysis of porcine MUC4 gene as a candidate gene for prolificacy QTL on SSC13 in an Iberian × Meishan F2 population
Background: Reproductive traits, such as prolificacy, are of great interest to the pig industry. Better understanding of their genetic architecture should help to increase the efficiency of pig productivity through the implementation of marker assisted selection (MAS) programmes. Results: The Mucin 4 (MUC4) gene has been evaluated as a candidate gene for a prolificacy QTL described in an Iberian × Meishan (Ib × Me) F2 intercross. For association analyses, two previously described SNPs (DQ124298:g.243A>G and DQ124298:g.344A>G) were genotyped in 347 pigs from the Ib × Me population. QTL for the number of piglets born alive (NBA) and for the total number of piglets born (TNB) were confirmed on SSC13 at positions 44 cM and 51 cM, respectively. The MUC4 gene was successfully located within the confidence intervals of both QTL. Only DQ124298:g.344A>G MUC4 polymorphism was significantly associated with both NBA and TNB (P-value < 0.05) with favourable effects coming from the Meishan origin. MUC4 expression level was determined in F2 sows displaying extreme phenotypes for the number of embryos (NE) at 30-32 days of gestation. Differences in the uterine expression of MUC4 were found between high (NE ≥ 13) and low (NE ≤ 11) prolificacy sows. Overall, MUC4 expression in high prolificacy sows was almost two-fold increased compared with low prolificacy sows. Conclusions: Our data suggest that MUC4 could play an important role in the establishment of an optimal uterine environment that would increase embryonic survival during pig gestation
Síntesis de kesterita Cu2ZnSn(S,Se)4 mediante métodos de hot-injection y solvotermal
En el presente trabajo se han sintetizado compuestos con estructura de kesterita Cu2ZnSn(S,Se)4 mediante métodos de síntesis “hot-injection” y solvotermal. Se ha analizado la efectividad de ambos procedimientos sobre las propiedades físico-químicas del material. Paralelamente, se ha estudiado la influencia de precursores y disolventes sobre la reactividad y la morfología del sistema. Los materiales desarrollados se han caracterizado estructural y microestructuralmente.Kesterite solid solution of Cu2ZnSn(S,Se)4 have been synthesized by “hot-injection” and solvothermal methods. The procedure effectiveness that affect to the physical and chemical properties of the final material have been analyzed. The influence of different raw materials and solvents has been investigated in order to improve the preparation procedure. The materials have been characterized structurally and morphologically
Real-Time and Low-Cost Sensing Technique Based on Photonic Bandgap Structures
This paper was published in OPTICS LETTERS and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OL.36.002707. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law[EN] A technique for the development of low-cost and high-sensitivity photonic biosensing devices is proposed and experimentally demonstrated. In this technique, a photonic bandgap structure is used as transducer, but its readout is performed by simply using a broadband source, an optical filter, and a power meter, without the need of obtaining the transmission spectrum of the structure; thus, a really low-cost system and real-time results are achieved. Experimental results show that it is possible to detect very low refractive index variations, achieving a detection limit below 2 x 10(-6) refractive index units using this low-cost measuring technique. (C) 2011 Optical Society of America[This work was funded by the Spanish Ministerio de Ciencia e Innovacion (MICINN) under contracts TEC2008-06333, JCI-009-5805, and TEC2008-05490. Support by the Universidad Politecnica de Valencia through program PAID-06-09 and the Conselleria d'Educacio through program GV-2010-031 is acknowledged.García Castelló, J.; Toccafondo, V.; Pérez Millán, P.; Sánchez Losilla, N.; Cruz, JL.; Andres, MV.; García-Rupérez, J. (2011). Real-Time and Low-Cost Sensing Technique Based on Photonic Bandgap Structures. Optics Letters. 36(14):2707-2709. https://doi.org/10.1364/OL.36.002707S270727093614Fan, X., White, I. M., Shopova, S. I., Zhu, H., Suter, J. D., & Sun, Y. (2008). Sensitive optical biosensors for unlabeled targets: A review. 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IEEE Journal of Selected Topics in Quantum Electronics, 16(3), 654-661. doi:10.1109/jstqe.2009.2032510Xu, D.-X., Vachon, M., Densmore, A., Ma, R., Delâge, A., Janz, S., … Schmid, J. H. (2010). Label-free biosensor array based on silicon-on-insulator ring resonators addressed using a WDM approach. Optics Letters, 35(16), 2771. doi:10.1364/ol.35.002771Skivesen, N., Têtu, A., Kristensen, M., Kjems, J., Frandsen, L. H., & Borel, P. I. (2007). Photonic-crystal waveguide biosensor. Optics Express, 15(6), 3169. doi:10.1364/oe.15.003169Lee, M. R., & Fauchet, P. M. (2007). Nanoscale microcavity sensor for single particle detection. Optics Letters, 32(22), 3284. doi:10.1364/ol.32.003284García-Rupérez, J., Toccafondo, V., Bañuls, M. J., Castelló, J. G., Griol, A., Peransi-Llopis, S., & Maquieira, Á. (2010). Label-free antibody detection using band edge fringes in SOI planar photonic crystal waveguides in the slow-light regime. Optics Express, 18(23), 24276. doi:10.1364/oe.18.024276Toccafondo, V., García-Rupérez, J., Bañuls, M. J., Griol, A., Castelló, J. G., Peransi-Llopis, S., & Maquieira, A. (2010). Single-strand DNA detection using a planar photonic-crystal-waveguide-based sensor. Optics Letters, 35(21), 3673. doi:10.1364/ol.35.003673Luff, B. J., Wilson, R., Schiffrin, D. J., Harris, R. D., & Wilkinson, J. S. (1996). Integrated-optical directional coupler biosensor. Optics Letters, 21(8), 618. doi:10.1364/ol.21.000618Sepúlveda, B., Río, J. S. del, Moreno, M., Blanco, F. J., Mayora, K., Domínguez, C., & Lechuga, L. M. (2006). Optical biosensor microsystems based on the integration of highly sensitive Mach–Zehnder interferometer devices. Journal of Optics A: Pure and Applied Optics, 8(7), S561-S566. doi:10.1088/1464-4258/8/7/s41Densmore, A., Vachon, M., Xu, D.-X., Janz, S., Ma, R., Li, Y.-H., … Schmid, J. H. (2009). Silicon photonic wire biosensor array for multiplexed real-time and label-free molecular detection. Optics Letters, 34(23), 3598. doi:10.1364/ol.34.003598Povinelli, M. L., Johnson, S. G., & Joannopoulos, J. D. (2005). Slow-light, band-edge waveguides for tunable time delays. Optics Express, 13(18), 7145. doi:10.1364/opex.13.007145Garcia, J., Sanchis, P., Martinez, A., & Marti, J. (2008). 1D periodic structures for slow-wave induced non-linearity enhancement. Optics Express, 16(5), 3146. doi:10.1364/oe.16.003146Pérez-Millán, P., Torres-Peiró, S., Cruz, J. L., & Andrés, M. V. (2008). Fabrication of chirped fiber Bragg gratings by simple combination of stretching movements. Optical Fiber Technology, 14(1), 49-53. doi:10.1016/j.yofte.2007.07.00
Characterization of the African swine fever virus decapping enzyme during infection
African swine fever virus (ASFV) infection is characterized by a progressive decrease in cellular protein synthesis with a concomitant increase in viral protein synthesis, though the mechanism by which the virus achieves this is still unknown. Decrease of cellular mRNA is observed during ASFV infection, suggesting that inhibition of cellular proteins is due to an active mRNA degradation process. ASFV carries a gene (Ba71V D250R/Malawi g5R) that encodes a decapping protein (ASFV-DP) that has a Nudix hydrolase motif and decapping activity in vitro. Here, we show that ASFV-DP was expressed from early times and accumulated throughout the infection with a subcellular localization typical of the endoplasmic reticulum, colocalizing with the cap structure and interacting with the ribosomal protein L23a. ASFV-DP was capable of interaction with poly(A) RNA in cultured cells, primarily mediated by the N-terminal region of the protein. ASFV-DP also interacted with viral and cellular RNAs in the context of infection, and its overexpression in infected cells resulted in decreased levels of both types of transcripts. This study points to ASFV-DP as a viral decapping enzyme involved in both the degradation of cellular mRNA and the regulation of viral transcripts
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