Allende-Cid, H., Canessa, E., Quezada, A., & Allende, H. (2011). An Improved Fuzzy Rule-Based Automated Trading Agent. Stud. Inform. Control, 20(2), 135–142.
Abstract: In this paper an improved Fuzzy Rule-Based Trading Agent is presented. The proposal consists in adding machine-learning-based methods to improve the overall performance of an automated agent that trades in futures markets. The modified Fuzzy Rule-Based Trading Agent has to decide whether to buy or sell goods, based on the spot and futures time series, gaining a profit from the price speculation. The proposal consists first in changing the membership functions of the fuzzy inference model (Gaussian and Sigmoidal, instead of triangular and trapezoidal). Then using the NFAR (Neuro-Fuzzy Autoregressive) model the relevant lags of the time series are detected, and finally a fuzzy inference system (Self-Organizing Neuro-Fuzzy Inference System) is implemented to aid the decision making process of the agent. Experimental results demonstrate that with the addition of these techniques, the improved agent considerably outperforms the original one.
|
Anabalon, A., Canfora, F., Giacomini, A., & Oliva, J. (2011). Black holes with gravitational hair in higher dimensions. Phys. Rev. D, 84(8), 10 pp.
Abstract: A new class of vacuum black holes for the most general gravity theory leading to second order field equations in the metric in even dimensions is presented. These space-times are locally anti-de Sitter in the asymptotic region, and are characterized by a continuous parameter that does not enter in the conserve charges, nor it can be reabsorbed by a coordinate transformation: it is therefore a purely gravitational hair. The black holes are constructed as a warped product of a two-dimensional space-time, which resembles the r-t plane of the Banados-Teitelboim-Zanelli black hole, times a warp factor multiplying the metric of a D – 2-dimensional Euclidean base manifold, which is restricted by a scalar equation. It is shown that all the Noether charges vanish. Furthermore, this is consistent with the Euclidean action approach: even though the black hole has a finite temperature, both the entropy and the mass vanish. Interesting examples of base manifolds are given in eight dimensions which are products of Thurston geometries, giving then a nontrivial topology to the black hole horizon. The possibility of introducing a torsional hair for these solutions is also discussed.
|
Anabalon, A., Canfora, F., Giacomini, A., & Oliva, J. (2011). Gribov ambiguity in asymptotically AdS three-dimensional gravity. Phys. Rev. D, 83(6), 7 pp.
Abstract: In this paper the zero modes of the de Donder gauge Faddeev-Popov operator for three-dimensional gravity with negative cosmological constant are analyzed. It is found that the AdS(3) vacuum produces (infinitely many) normalizable smooth zero modes of the Faddeev-Popov operator. On the other hand, it is found that the Banados-Teitelboim-Zanelli black hole (including the zero mass black hole) does not generate zero modes. This differs from the usual Gribov problem in QCD where, close to the maximally symmetric vacuum, the Faddeev-Popov determinant is positive definite while "far enough'' from the vacuum it can vanish. This suggests that the zero mass Banados-Teitelboim-Zanelli black hole could be a suitable ground state of three-dimensional gravity with negative cosmological constant. Because of the kinematic origin of this result, it also applies for other covariant gravity theories in three dimensions with AdS(3) as maximally symmetric solution, such as new massive gravity and topologically massive gravity. The relevance of these results for supersymmetry breaking is pointed out.
|
Anabalon, A., Deruelle, N., Tempo, D., & Troncoso, R. (2011). Remarks On The Myers-Perry And Einstein-Gauss-Bonnet Rotating Solutions. Int. J. Mod. Phys. D, 20(5), 639–647.
Abstract: The Kerr-type solutions of the five-dimensional Einstein and Einstein-Gauss-Bonnet equations look pretty similar when written in Kerr-Schild form. However the Myers-Perry spacetime is circular whereas the rotating solution of the Einstein-Gauss-Bonnet theory is not. We explore some consequences of this difference in particular regarding the (non) existence of Boyer-Lindquist-type coordinates and the extension of the manifold.
|
Aquea, F., Vega, A., Timmermann, T., Poupin, M. J., & Arce-Johnson, P. (2011). Genome-wide analysis of the SET DOMAIN GROUP family in Grapevine. Plant Cell Reports, 30(6), 1087–1097.
Abstract: The SET DOMAIN GROUP (SDG) proteins represent an evolutionarily-conserved family of epigenetic regulators present in eukaryotes and are putative candidates for the catalysis of lysine methylation in histones. Plant genomes analyses of this family have been performed in arabidopsis, maize, and rice and functional studies have shown that SDG genes are involved in the control of plant development. In this work, we describe the identification and structural characterization of SDG genes in the Vitis vinifera genome. This analysis revealed the presence of 33 putative SDG genes that can be grouped into different classes, as it has been previously described for plants. In addition to the SET domain, the proteins identified possessed other domains in the different classes. As part of our study regarding the growth and development of grapevine, we selected eight genes and their expression levels were analyzed in representative vegetative and reproductive organs of this species. The selected genes showed different patterns of expression during inflorescence and fruit development, suggesting that they participate in these processes. Furthermore, we showed that the expression of selected SDGs changes during viral infection, using as a model Grapevine Leafroll Associated Virus 3-infected symptomatic grapevine leaves and fruits. Our results suggest that developmental changes caused by this virus could be the result of alterations in SDG expression.
|
Arias, M. B., Poupin, M. J., & Lardies, M. A. (2011). Plasticity of life-cycle, physiological thermal traits and Hsp70 gene expression in an insect along the ontogeny: Effect of temperature variability. J. Therm. Biol., 36(6), 355–362.
Abstract: It is considered that extreme environmental temperature, rather than mean temperatures exert a selective pressure in ectotherms. Consequently, it is important to understand how the predicted increase in temperature variance with a higher frequency of extreme events in climate change is likely to impact on organisms. Thermal tolerance traits (i.e. chill-coma, recovery time, Hsp70 expression) are directly linked with performance in ectotherms and have consequences in life-history traits. We examined the effects of temperature variability on thermal tolerance and life-history traits through ontogeny of an insect with a complex life-cycle: the yellow mealworm beetle Tenebrio molitor. We established two common gardens with 100 recently ovoposited eggs each. Larvae were reared from hatching to adult on either a variable (mean=18 degrees C and a variance of 6.8 degrees C) or constant (18 +/- 1 degrees C) thermal environment. Development rate and growth rate were similar between thermal environments. Results indicate that larvae reared in a variable environment are more cold-tolerant than larvae of a constant environment. Interestingly, these results are reversed in the adult stage, outlining an inter-stage physiological cost. Gene expression pattern of an Hsp70 gene was well correlated with larval thermotolerance to cold in the variable environment but higher gene expression in adults is not correlated with individual's thermotolerance. We conclude that chill-coma, recovery time and Hsp70 gene expression are plastic in response to a thermal environment but also change significantly their responses depending on the ontogenetic stage, implying that the response of adult individuals is linked to early stages of the life-cycle. (C) 2011 Elsevier Ltd. All rights reserved,
|
Bustamante, M., & Lefranc, G. (2011). Degradation Model Of Breast Imaging By Dispersed Radiation. Proc. Rom. Acad. Ser. A-Math. Phys., 12(4), 347–352.
Abstract: This paper presents a model of interaction of radiation on breast, based on Bosso's filter. This model is used to improve mammographic images for early cancer diagnosis, to be more accurate and to detect cluster of microcalcifications. The model is based on degradation of breast image produced by dispersed radiation using the Bosso's filter, developed earlier.
|
Chandia, O. (2011). The b ghost of the pure spinor formalism is nilpotent. Phys. Lett. B, 695(1-4), 312–316.
Abstract: The ghost for world-sheet reparametrization invariance is not a fundamental field in the pure spinor formalism. It is written as a combination of pure spinor variables which have conformal dimension two and such that it commutes with the BRST operator to give the world-sheet stress tensor. We show that the ghost variable defined in this way is nilpotent since the OPE of b with itself does not have singularities. (C) 2010 Elsevier B.V. All rights reserved.
|
Chandia, O., Linch, W. D., & Vallilo, B. C. (2011). Compactification of the heterotic pure spinor superstring II. J. High Energy Phys., (10), 22 pp.
Abstract: We study compactifications of the heterotic pure spinor superstring to six and four dimensions focusing on two simple Calabi-Yau orbifolds. We show that the correct spectrum can be reproduced only if, in the twisted sector, there remain exactly 5 and 2 pure spinor components untwisted, respectively. This naturally defines a “small” Hilbert space of untwisted variables. We point out that the cohomology of the reduced differential on this small Hilbert space can be used to describe the states in the untwisted sector, provided certain auxiliary constraints are defined. In dimension six, the mismatch between the number of pure spinor components in the small Hilbert space and the number of components of a six-dimensional pure spinor is interpreted as providing the projective measure on the analytic subspace (in the projective description) of harmonic superspace.
|
|
Clerc, M. G., Rica, S., & Tredicce, J. (2011). Instabilities and Non-equilibrium Structures. On the occasion of the 60th birthday of Pierre Coullet. Eur. Phys. J. D, 62(1), 1–4.
|
Dauelsberg, P., Matus, J. T., Poupin, M. J., Leiva-Ampuero, A., Godoy, F., Vega, A., et al. (2011). Effect of pollination and fertilization on the expression of genes related to floral transition, hormone synthesis and berry development in grapevine. J. Plant Physiol., 168(14), 1667–1674.
Abstract: In the present work, the effect of assisted fertilization on anatomical, morphological and gene expression changes occurring in carpels and during early stages of berry development in Vitis vinifera were studied. Inflorescences were emasculated before capfall, immediately manually pollinated (EP) and fruit development was compared to emasculated but non-pollinated (ENP) and self-pollinated inflorescences (NESP). The diameter of berries derived from pollinated flowers (EP and NESP) was significantly higher than from non-pollinated flowers (ENP) at 21 days after emasculation/pollination (DAE), and a rapid increase in the size of the inner mesocarp, together with the presence of an embryo-like structure, were observed. The expression of gibberellin oxidases (GA200x and GA2ox), anthranilate synthase (related to auxin synthesis) and cytokinin synthase coding genes was studied to assess the relationship between hormone synthesis and early berry development, while flower patterning genes were analyzed to describe floral transition. Significant expression changes were found for hormone-related genes, suggesting that their expression at early stages of berry development (13 DAE) is related to cell division and differentiation of mesocarp tissue at a later stage (21 DAE). Expression of hormone-related genes also correlates with the expression of VvHB13, a gene related to mesocarp expansion, and with an increased repression of floral patterning genes (PISTILLATA and TM6), which may contribute to prevent floral transition inhibiting fruit growth before fertilization takes place. (C) 2011 Elsevier GmbH. All rights reserved.
|
Domic, N. G., Goles, E., & Rica, S. (2011). Dynamics and complexity of the Schelling segregation model. Phys. Rev. E, 83(5), 13 pp.
Abstract: In this paper we consider the Schelling social segregation model for two different populations. In Schelling's model, segregation appears as a consequence of discrimination, measured by the local difference between two populations. For that, the model defines a tolerance criterion on the neighborhood of an individual, indicating wether the individual is able to move to a new place or not. Next, the model chooses which of the available unhappy individuals really moves. In our work, we study the patterns generated by the dynamical evolution of the Schelling model in terms of various parameters or the initial condition, such as the size of the neighborhood of an inhabitant, the tolerance, and the initial number of individuals. As a general rule we observe that segregation patterns minimize the interface of zones of different people. In this context we introduce an energy functional associated with the configuration which is a strictly decreasing function for the tolerant people case. Moreover, as far as we know, we are the first to notice that in the case of a non-strictly-decreasing energy functional, the system may segregate very efficiently.
|
Donoso, R. A., Perez-Pantoja, D., & Gonzalez, B. (2011). Strict and direct transcriptional repression of the pobA gene by benzoate avoids 4-hydroxybenzoate degradation in the pollutant degrader bacterium Cupriavidus necator JMP134. Environ. Microbiol., 13(6), 1590–1600.
Abstract: As other environmental bacteria, Cupriavidus necator JMP134 uses benzoate as preferred substrate in mixtures with 4-hydroxybenzoate, strongly inhibiting its degradation. The mechanism underlying this hierarchical use was studied. A C. necator benA mutant, defective in the first step of benzoate degradation, is unable to metabolize 4-hydroxybenzoate when benzoate is also included in the medium, indicating that this substrate and not one of its catabolic intermediates is directly triggering repression. Reverse transcription polymerase chain reaction analysis revealed that 4-hydroxybenzoate 3-hydroxylase-encoding pobA transcripts are nearly absent in presence of benzoate and a fusion of pobA promoter to lacZ reporter confirmed that benzoate drastically decreases the transcription of this gene. Expression of pobA driven by a heterologous promoter in C. necator benA mutant, allows growth on 4-hydroxybenzoate in presence of benzoate, overcoming its repressive effect. In contrast with other bacteria, regulators of benzoate catabolism do not participate in repression of 4-hydroxybenzoate degradation. Moreover, the effect of benzoate on pobA promoter can be observed in heterologous strains with the sole presence of PobR, the transcriptional activator of pobA gene, indicating that PobR is enough to fully reproduce the phenomenon. This novel mechanism for benzoate repression is probably mediated by direct action of benzoate over PobR.
|
Feo-Valero, M., Garcia-Menendez, L., & Garrido-Hidalgo, R. (2011). Valuing Freight Transport Time using Transport Demand Modelling: A Bibliographical Review. Transp. Rev., 31(5), 625–651.
Abstract: The value of time for freight transport is of major importance in infrastructure-related cost-benefit analysis and yet its study has been largely neglected when compared with its passenger counterpart. In fact, one of the attributes that could decide the profitability of a project is how much can be saved if freight vehicles use new infrastructure. Despite being the primary benefit of most investments in transport infrastructure, researchers have not yet reached agreement over either the size or the nature of the values of time that should be used when evaluating projects. This article provides a review of the estimation of freight value of time through transport demand modelling and extant empirical evidence on this topic. Similarly, the bibliographic review of studies undertaken has allowed us to pinpoint the most critical issues when modelling freight transport demand and the position of various research teams regarding these aspects. Such issues include identifying the decision-maker, heterogeneity in the transport flows and transport attributes considered by decision-makers.
|
Galanopoulos, P., Girela, D., & Hernandez, R. (2011). Univalent Functions, VMOA and Related Spaces. J. Geom. Anal., 21(3), 665–682.
Abstract: This paper is concerned mainly with the logarithmic Bloch space B(log) which consists of those functions f which are analytic in the unit disc D and satisfy sup(|z|<1)(1-|z|) log 1/1-|z| |f' (z)|<infinity, and the analytic Besov spaces Bp, 1 <= p < infinity. They are all subspaces of the space VMOA. We study the relation between these spaces, paying special attention to the membership of univalent functions in them. We give explicit examples of: A bounded univalent function in U(p>1) B(P) Bp but not in the logarithmic Bloch space. A bounded univalent function in B(log) but not in any of the Besov spaces B(p) with p < 2. We also prove that the situation changes for certain subclasses of univalent functions. Namely, we prove that the convex univalent functions in D which belong to any of the spaces B(0), VMOA, B(p) (1 <= p <= infinity), Blog, or some other related spaces are the same, the bounded ones. We also consider the question of when the logarithm of the derivative, log g', of a univalent function g belongs to Besov spaces. We prove that no condition on the growth of the Schwarzian derivative Sg of g guarantees log g' is an element of B(p). On the other hand, we prove that the condition integral(D) (1-|z|(2))(2p-2) |Sg(z)|(p) d A(z)<infinity implies that log g' is an element of B(p) and that this condition is sharp. We also study the question of finding geometric conditions on the image domain g(D) which imply that log g' lies in Bp. First, we observe that the condition of g( D) being a convex Jordan domain does not imply this. On the other hand, we extend results of Pommerenke and Warschawski, obtaining for every p is an element of (1, infinity), a sharp condition on the smoothness of a Jordan curve Gamma which implies that if g is a conformal mapping from D onto the inner domain of Gamma, then log g' is an element of B(p).
|
Garcia-Echauri, S. A., Gidekel, M., Gutierrez-Moraga, A., Santos, L., & De Leon-Rodriguez, A. (2011). Isolation and phylogenetic classification of culturable psychrophilic prokaryotes from the Collins glacier in the Antarctica. Folia Microbiol., 56(3), 209–214.
Abstract: Culturable psychrophilic prokaryotes were obtained of samples of glacier sediment, seaside mud, glacier melted ice, and Deschampsia antarctica rhizosphere from Collins glacier, Antarctica. The taxonomic classification was done by a culture-dependent molecular approach involving the Amplified Ribosomal DNA Restriction Analysis. Two hundred sixty colonies were successfully isolated and sub-cultivated under laboratory conditions. The analysis showed a bacterial profile dominated by Beta-proteobacteria (35.2%) followed by Gamma-proteobacteria (18.5%), Alpha-proteobacteria (16.6%), Gram-positive with high GC content (13%), Cytophaga-Flavobacterium-Bacteroides (13%) and Gram-positive with low GC content (3.7%). Eleven of the isolates have been reported previously and the others microorganisms remain uncharacterized. The isolated microorganisms here could be a potential source for biotechnological products, such as cold-active enzymes and secondary metabolites.
|
Goldstein-Daruech, N., Cope, E. K., Zhao, K. Q., Vukovic, K., Kofonow, J. M., Doghramji, L., et al. (2011). Tobacco Smoke Mediated Induction of Sinonasal Microbial Biofilms. PLoS One, 6(1), 7 pp.
Abstract: Cigarette smokers and those exposed to second hand smoke are more susceptible to life threatening infection than nonsmokers. While much is known about the devastating effect tobacco exposure has on the human body, less is known about the effect of tobacco smoke on the commensal and commonly found pathogenic bacteria of the human respiratory tract, or human respiratory tract microbiome. Chronic rhinosinusitis (CRS) is a common medical complaint, affecting 16% of the US population with an estimated aggregated cost of $6 billion annually. Epidemiologic studies demonstrate a correlation between tobacco smoke exposure and rhinosinusitis. Although a common cause of CRS has not been defined, bacterial presence within the nasal and paranasal sinuses is assumed to be contributory. Here we demonstrate that repetitive tobacco smoke exposure induces biofilm formation in a diverse set of bacteria isolated from the sinonasal cavities of patients with CRS. Additionally, bacteria isolated from patients with tobacco smoke exposure demonstrate robust in vitro biofilm formation when challenged with tobacco smoke compared to those isolated from smoke naive patients. Lastly, bacteria from smoke exposed patients can revert to a non-biofilm phenotype when grown in the absence of tobacco smoke. These observations support the hypothesis that tobacco exposure induces sinonasal biofilm formation, thereby contributing to the conversion of a transient and medically treatable infection to a persistent and therapeutically recalcitrant condition.
|
Goles, E., & Rica, S. (2011). Irreversibility and spontaneous appearance of coherent behavior in reversible systems. Eur. Phys. J. D, 62(1), 127–137.
Abstract: There is empirical evidence that long time numerical simulations of conservative and reversible partial differential equations evolve, as a general rule (exceptions are the integrable models), towards an equilibrium state that is mainly a coherent structure plus small fluctuations inherent in the conservative and reversible character of the original system. The fluctuations account for the energy difference between the initial configuration and the one of the coherent structure. If the energy is not small enough, then the intrinsic fluctuations may destroy the coherent structure. Thus we arrive to the conclusion that a transition arises from a non-coherent state to a coherent structure as we decrease the initial energy below a critical value. This phenomenon has been successfully observed in various numerical simulations. In this article, we stress that this general behavior is also observed in reversible and conservative cellular automata as in the Q2R model. We point out that this conservative and reversible cellular automata is ab initio deterministic and therefore all our numerical computations are not affected by an approximation of any kind.
|
Goles, E., Guillon, P., & Rapaport, I. (2011). Traced communication complexity of cellular automata. Theor. Comput. Sci., 412(30), 3906–3916.
Abstract: We study cellular automata with respect to a new communication complexity problem: each of two players know half of some finite word, and must be able to tell whether the state of the central cell will follow a given evolution, by communicating as little as possible between each other. We present some links with classical dynamical concepts, especially equicontinuity, expansivity, entropy and give the asymptotic communication complexity of most elementary cellular automata. (C) 2011 Elsevier B.V. All rights reserved.
|
Goles, E., Meunier, P. E., Rapaport, I., & Theyssier, G. (2011). Communication complexity and intrinsic universality in cellular automata. Theor. Comput. Sci., 412(1-2), 2–21.
Abstract: The notions of universality and completeness are central in the theories of computation and computational complexity. However, proving lower bounds and necessary conditions remains hard in most cases. In this article, we introduce necessary conditions for a cellular automaton to be “universal”, according to a precise notion of simulation, related both to the dynamics of cellular automata and to their computational power. This notion of simulation relies on simple operations of space-time rescaling and it is intrinsic to the model of cellular automata. intrinsic universality, the derived notion, is stronger than Turing universality, but more uniform, and easier to define and study. Our approach builds upon the notion of communication complexity, which was primarily designed to study parallel programs, and thus is, as we show in this article, particulary well suited to the study of cellular automata: it allowed us to show, by studying natural problems on the dynamics of cellular automata, that several classes of cellular automata, as well as many natural (elementary) examples, were not intrinsically universal. (C) 2010 Elsevier B.V. All rights reserved.
|
