
Bunster, C., & Gomberoff, A. (2017). Gravitational domain walls and the dynamics of the gravitational constant G. Phys. Rev. D, 96(2), 9 pp.
Abstract: From the point of view of elementary particle physics the gravitational constant G is extraordinarily small. This has led to ask whether it could have decayed to its present value from an initial one commensurate with microscopical units. A mechanism that leads to such a decay is proposed herein. It is based on assuming that G may take different values within regions of the universe separated by a novel kind of domain wall, a “Gwall”. The idea is implemented by introducing a gauge potential A, and its conjugate D, which determines the value of G as an integration constant rather than a fundamental constant. The value of G jumps when one goes through a Gwall. The procedure extends one previously developed for the cosmological constant, but the generalization is far from straightforward: (i) The intrinsic geometry of a Gwall is not the same as seen from its two sides, because the second law of black hole thermodynamics mandates that the jump in G must cause a discontinuity in the scale of length. (ii) The size of the decay step in G is controlled by a function G(D) which may be chosen so as to diminish the value of G towards the asymptote G = 0, without fine tuning. It is shown that: (i) The dynamics of the gravitational field with G treated as a dynamical variable, coupled to Gwalls and matter, follows from an action principle, which is given. (ii) A particle that impinges on a Gwall may be refracted or reflected. (iii) The various forces between two particles change when a Gwall is inserted in between them. (iv) Gwalls may be nucleated trough tunneling and thermal effects. The semiclassical probabilities are evaluated. (v) If the action principle is constructed properly, the entropy of a black hole increases when the value of the gravitational constant is changed through the absorption of a Gwall by the hole.



Cabrera, I., Villalon, J., & Chavez, J. (2017). Blending Communities and TeamBased Learning in a Programming Course. IEEE Trans. Educ., 60(4), 288–295.
Abstract: In recent years, engineering education teachers have needed to incorporate technologysupported collaboration to enhance learning. Implementing these activities requires course redesign, which must be meticulous for their full potential to be reached. This can require a lot of work for first time users, which can be a barrier to implementation. Educational design patterns alleviate this burden by facilitating new course design with practices demonstrated to promote student engagement. This paper reports on the redesign of an introductory programming course and its experimental evaluation. The redesign was based on the community of inquiry learning framework (CoL), using design patterns from online Web communities and teambased learning (TBL). The evaluation included 562 students, 117 of them randomly assigned to two different experimental groups. One group used a CoL approach, and the other a blended TBL and CoL methodology. The remaining students were assigned to control groups. Results showed that students in the experimental groups outperformed those in the control group by the end of the semester, while the experimental CoL and TBL methodology helped students achieve a higher level of understanding in a shorter period of time due to increased participation rates. These data provide empirical evidence of the learning gains offered by online learning communities, and the way in which educational design patterns can facilitate course redesign.



Caceres, C., Moffat, R., & Pakalnis, R. (2017). Evaluation of flexural failure of sill mats using classical beam theory and numerical models. Int. J. Rock Mech. Min. Sci., 99, 21–27.



Caceres, G., Fullenkamp, K., Montane, M., Naplocha, K., & Dmitruk, A. (2017). Encapsulated Nitrates Phase Change Material Selection for Use as Thermal Storage and Heat Transfer Materials at High Temperature in Concentrated Solar Power Plants. Energies, 10(9), 21 pp.
Abstract: In the present paper, the finite element method is used to perform an exhaustive analysis of the thermal behavior of encapsulated phase change materials (EPCMs), which includes an assessment of several materials in order to identify the best combination of PCM and shell material in terms of thermal energy storage, heat transfer rate, cost of materials, limit of pressure that they can support and other criteria. It is possible to enhance the heat transfer rate without a considerable decrease of the thermal energy storage density, by increasing the thickness of the shell. In the first examination of thermomechanical coupling effects, the technical feasibility can be determined if the EPCM dimensions are designed considering the thermal expansion and the tensile strength limit of the materials. Moreover, when a proper EPCM shell material and PCM composition is used, and compared with the current storage methods of concentrated solar power (CSP) plants, the use of EPCM allows one to enhance significantly the thermal storage, reaching more than 1.25 GJ/m(3) of energy density.



Campos, J. L., del Rio, A. V., Pedrouso, A., Raux, P., Giustinianovich, E. A., & MosqueraCorral, A. (2017). Granular biomass floatation: A simple kinetic/stoichiometric explanation. Chem. Eng. J., 311, 63–71.
Abstract: Floatation events are commonly observed in anammox, denitrifying and anaerobic granular systems mostly subjected to overloading conditions. Although several operational strategies have been proposed to avoid floatation of granular biomass, until now, there is no consensus about the conditions responsible for this phenomenon. In the present study, a simple explanation based on kinetic and stoichiometric principles defining the aforementioned processes is provided. The operational zones corresponding to evaluated parameters where risk of floatation exists are defined as a function of substrate concentration in the bulk liquid and the radius of the granule. Moreover, the possible control of biomass floatation by changing the operating temperature was analyzed. Defined operational zones and profiles fit data reported in literature for granular biomass floatation events. From the study the most influencing parameter on floatation occurrence has been identified as the substrate concentration in the bulk media. (C) 2016 Elsevier B.V. All rights reserved.



Canessa, E., & Chaigneau, S. (2017). Response surface methodology for estimating missing values in a pareto genetic algorithm used in parameter design. Ing. Invest., 37(2), 89–98.
Abstract: We present an improved Pareto Genetic Algorithm (PGA), which finds solutions to problems of robust design in multiresponse systems with 4 responses and as many as 10 control and 5 noise factors. Because some response values might not have been obtained in the robust design experiment and are needed in the search process, the PGA uses Response Surface Methodology (RSM) to estimate them. Not only the PGA delivered solutions that adequately adjusted the response means to their target values, and with low variability, but also found more Pareto efficient solutions than a previous version of the PGA. This improvement makes it easier to find solutions that meet the tradeoff among variance reduction, mean adjustment and economic considerations. Furthermore, RSM allows estimating outputs' means and variances in highly nonlinear systems, making the new PGA appropriate for such systems.



Canfora, F., Oh, S. H., & SalgadoRebolledo, P. (2017). Gravitational catalysis of merons in EinsteinYangMills theory. Phys. Rev. D, 96(8), 10 pp.
Abstract: We construct regular configurations of the EinsteinYangMills theory in various dimensions. The gauge field is of merontype: it is proportional to a pure gauge (with a suitable parameter lambda determined by the field equations). The corresponding smooth gauge transformation cannot be deformed continuously to the identity. In the threedimensional case we consider the inclusion of a ChernSimons term into the analysis, allowing lambda to be different from its usual value of 1/2. In four dimensions, the gravitating meron is a smooth Euclidean wormhole interpolating between different vacua of the theory. In five and higher dimensions smooth meronlike configurations can also be constructed by considering warped products of the threesphere and lowerdimensional Einstein manifolds. In all cases merons (which on flat spaces would be singular) become regular due to the coupling with general relativity. This effect is named “gravitational catalysis of merons”.



Canfora, F. E., Dudal, D., Justo, I. F., Pais, P., SalgadoRebolledo, P., Rosa, L., et al. (2017). Double nonperturbative gluon exchange: An update on the softPomeron contribution to pp scattering. Phys. Rev. C, 96(2), 8 pp.
Abstract: We employ a set of recent, theoretically motivated fits to nonperturbative unquenched gluon propagators to check on how far double gluon exchange can be used to describe the soft sector of pp scattering data (total and differential cross section). In particular, we use the refined GribovZwanziger gluon propagator (as arising from dealing with the Gribov gauge fixing ambiguity) and the massive Cornwalltype gluon propagator (as motivated from DysonSchwinger equations) in conjunction with a perturbative quarkgluon vertex, next to a model based on the nonperturbative quarkgluon MarisTandy vertex, popular from BetheSalpeter descriptions of hadronic bound states. We compare the cross sections arising from these models with older ISR and more recent TOTEM and ATLAS data. The lower the value of total energy root s, the better the results appear to be.



Carrasco, J. A., & Smith, L. (2017). Search at the Margin. Am. Econ. Rev., 107(10), 3146–3181.
Abstract: We extend search theory to multiple indivisible units and perfectly divisible assets, solving them respectively with induction and recursion. Buyer demands and prices are random, and the seller can partially exercise orders. With divisible assets, the Bellman value function is increasing and strictly concave, and the optimal reservation price falls in the position, reflecting increasing holding costs (opportunity cost of delaying optionality for inframarginal units). The marginal value exists, and is strictly convex with a falling purchase cap density. Our model is amenable to pricequantity bargaining; e.g., greater buyer bargaining power is tantamount to greater search frictions.



Carreno, A., Aros, A. E., Otero, C., Polanco, R., Gacitua, M., ArratiaPerez, R., et al. (2017). Substituted bidentate and ancillary ligands modulate the bioimaging properties of the classical Re(I) tricarbonyl core with yeasts and bacteria (vol 41, pg 2140, 2017). New J. Chem., 41(7), 2826.



Chandia, O., Linch, W. D., & Vallilo, B. C. (2017). Master symmetry in the AdS(5) x S5 pure spinor string. J. High Energy Phys., (1), 15 pp.
Abstract: We lift the set of classical nonlocal symmetries recently studied by Klose, Loebbert, and Winkler in the context of Z(2) cosecs to the pure spinor description of the superstring in the AdS(5) x S5 background.



Chuaqui, M., Hernandez, R., & Martin, M. J. (2017). Affine and linear invariant families of harmonic mappings. Math. Ann., 367(34), 1099–1122.
Abstract: We study the order of affine and linear invariant families of planar harmonic mappings in the unit disk. By using the famous shear construction of Clunie and SheilSmall, we construct a function to determine the order of the family of mappings with bounded Schwarzian norm. The result shows that finding the order of the class SH of univalent harmonic mappings can be formulated as a question about Schwarzian norm and, in particular, our result shows consistency between the conjectured order of SH and the Schwarzian norm of the harmonic Koebe function.



Concha, P. K., Merino, N., & Rodriguez, E. K. (2017). Lovelock gravities from BornInfeld gravity theory. Phys. Lett. B, 765, 395–401.
Abstract: We present a BornInfeld gravity theory based on generalizations of Maxwell symmetries denoted as Cm. We analyze different configuration limits allowing to recover diverse Lovelock gravity actions in six dimensions. Further, the generalization to higher even dimensions is also considered. (C) 2016 The Authors. Published by Elsevier B.V.



Contreras, M., Pellicer, R., & Villena, M. (2017). Dynamic optimization and its relation to classical and quantum constrained systems. Physica A, 479, 12–25.
Abstract: We study the structure of a simple dynamic optimization problem consisting of one state and one control variable, from a physicist's point of view. By using an analogy to a physical model, we study this system in the classical and quantum frameworks. Classically, the dynamic optimization problem is equivalent to a classical mechanics constrained system, so we must use the Dirac method to analyze it in a correct way. We find that there are two secondclass constraints in the model: one fix the momenta associated with the control variables, and the other is a reminder of the optimal control law. The dynamic evolution of this constrained system is given by the Dirac's bracket of the canonical variables with the Hamiltonian. This dynamic results to be identical to the unconstrained one given by the Pontryagin equations, which are the correct classical equations of motion for our physical optimization problem. In the same Pontryagin scheme, by imposing a closedloop lambdastrategy, the optimality condition for the action gives a consistency relation, which is associated to the HamiltonJacobiBellman equation of the dynamic programming method. A similar result is achieved by quantizing the classical model. By setting the wave function Psi (x, t) = e(is(x,t)) in the quantum Schrodinger equation, a nonlinear partial equation is obtained for the S function. For the righthand side quantization, this is the HamiltonJacobiBellman equation, when S(x, t) is identified with the optimal value function. Thus, the HamiltonJacobiBellman equation in Bellman's maximum principle, can be interpreted as the quantum approach of the optimization problem. (C) 2017 Elsevier B.V. All rights reserved.



Cortes, M. P., Mendoza, S. N., Travisany, D., Gaete, A., Siegel, A., Cambiazo, V., et al. (2017). Analysis of Piscirickettsia salmonis Metabolism Using GenomeScale Reconstruction, Modeling, and Testing. Front. Microbiol., 8, 15 pp.
Abstract: Piscirickettsia salmonis is an intracellular bacterial fish pathogen that causes piscirickettsiosis, a disease with highly adverse impact in the Chilean salmon farming industry. The development of effective treatment and control methods for piscireckttsiosis is still a challenge. To meet it the number of studies on P. salmonis has grown in the last couple of years but many aspects of the pathogen's biology are still poorly understood. Studies on its metabolism are scarce and only recently a metabolic model for reference strain LF89 was developed. We present a new genomescale model for P. salmonis LF89 with more than twice as many genes as in the previous model and incorporating specific elements of the fish pathogen metabolism. Comparative analysis with models of different bacterial pathogens revealed a lower flexibility in P. salmonis metabolic network. Through constraintbased analysis, we determined essential metabolites required for its growth and showed that it can benefit from different carbon sources tested experimentally in new defined media. We also built an additional model for strain A115972, and together with an analysis of P. salmonis pangenome, we identified metabolic features that differentiate two main species clades. Both models constitute a knowledgebase for P. salmonis metabolism and can be used to guide the efficient culture of the pathogen and the identification of specific drug targets.



Crutchik, D., Morales, N., VazquezPadin, J. R., & Garrido, J. M. (2017). Enhancement of struvite pellets crystallization in a fullscale plant using an industrial grade magnesium product. Water Sci. Technol., 75(3), 609–618.
Abstract: A fullscale struvite crystallization system was operated for the treatment of the centrate obtained from the sludge anaerobic digester in a municipal wastewater treatment plant. Additionally, the feasibility of an industrial grade Mg(OH) (2) as a cheap magnesium and alkali source was also investigated. The struvite crystallization plant was operated for two different periods: period I, in which an influent with low phosphate concentration (34.0 mg P . L (1)) was fed to the crystallization plant; and period II, in which an influent with higher phosphate concentration (68.0 mg P . L (1)) was used. A high efficiency of phosphorus recovery by struvite crystallization was obtained, even when the effluent treated had a high level of alkalinity. Phosphorus recovery percentage was around 77%, with a phosphate concentration in the effluent between 10.0 and 30.0 mg P .L 1. The experiments gained struvite pellets of 0.5 5.0 mm size. Moreover, the consumption of Mg(OH) (2) was estimated at 1.5 mol Mg added . mol P recovered (1). Thus, industrial grade Mg(OH) (2) can be an economical alternative as magnesium and alkali sources for struvite crystallization at industrial scale.



Deacon, R. M. J., Hurley, M. J., Rebolledo, C. M., Snape, M., Altimiras, F. J., Farias, L., et al. (2017). Nrf2: a novel therapeutic target in fragile X syndrome is modulated by NNZ2566. Genes Brain Behav., 16(7), 1–10.
Abstract: Fragile Xassociated disorders are a family of genetic conditions resulting from the partial or complete loss of fragile X mental retardation protein (FMRP). Among these disorders, fragile X syndrome (FXS) is the most common cause of inherited intellectual disability and autism. Progress in basic neuroscience has led to identification of molecular targets for treatment in FXS; however, there is a gap in translation to targeted therapies in humans. This study introduces a novel therapeutic target for FXS, nuclear factor (erythroidderived 2)like 2 (Nrf2), a transcription factor known to induce expression of over 100 cytoprotective genes. We also show that NNZ2566, a drug that has successfully completed a phase 2 clinical trial in FXS, is effective in modulating this target in FXS, partially reversing the FXS phenotype; NNZ2566 has a therapeutic role as Nrf2 activator. Effectively, treatment with NNZ2566 normalizes the translocation of Nrf2 to the nucleus, inducing expression of numerous oxidative stressrelated genes including NQO1 (NAD(P) H dehydrogenase quinone 1), GSTalpha 1 (glutathione Stransferase alpha1) and EH (epoxide hydrolase) and has a knockdown effect on Ecadherin. In summary, the Nrf2/ARE (antioxidant response element) pathway appears to be a novel promising therapeutic target for FXS and NNZ2566 appears to be acting as an activator of the Nrf2/ARE pathway and suggests a potential benefit across multiple symptoms that could be associated with the pathobiological processes underlying FXS.



del Rio, A. V., da Silva, T., Martins, T. H., Foresti, E., Campos, J. L., Mendez, R., et al. (2017). Partial NitritationAnammox Granules: ShortTerm Inhibitory Effects of Seven Metals on Anammox Activity. Water Air Soil Pollut., 228(11), 9 pp.
Abstract: The inhibitory effect of seven different metals on the specific anammox activity of granular biomass, collected from a single stage partial nitritation/anammox reactor, was evaluated. The concentration of each metal that led to a 50% inhibition concentration (IC50) was 19.3 mg Cu+2/L, 26.9 mg Cr+2/L, 45.6 mg Pb+2/L, 59.1 mg Zn+2/L, 69.2 mg Ni+2/L, 174.6 mg Cd+2/L, and 175.8 mg Mn+2/L. In experiments performed with granules mechanically disintegrated (flocculentlike sludge), the IC50 for Cd+2 corresponded to a concentration of 93.1 mg Cd+2/L. These results indicate that the granular structure might act as a physical barrier to protect anammox bacteria from toxics. Furthermore, the presence of an external layer of ammonia oxidizing bacteria seems to mitigate the inhibitory effect of the metals, as the values of IC50 obtained in this study for anammox activity were higher than those previously reported for anammox granules. Additionally, the results obtained confirmed that copper is one of the most inhibitory metals for anammox activity and revealed that chromium, scarcely studied yet, has a similar potential inhibitory effect.



del Rio, A. V., Stachurski, A., Mendez, R., Campos, J. L., SurmaczGorska, J., & MosqueraCorral, A. (2017). Short and longterm orange dye effects on ammonium oxidizing and anammox bacteria activities. Water Sci. Technol., 76(1), 79–86.
Abstract: The effects of orange azo dye over ammonia oxidizing bacteria (AOB) and anammox bacteria activities were tested. Performed batch tests indicated that concentrations lower than 650 mg(orange)/L stimulated AOB activity, while anammox bacteria activity was inhibited at concentrations higher than 25 mg(orange)/L. Longterm performance of a continuous stirred tank reactor (CSTR) for the partial nitritation and a sequencing batch reactor (SBR) for the anammox process was tested in the presence of 50 mg(orange)/L. In the case of the partial nitritation process, both the biomass concentration and the specific AOB activity increased after 50 days of orange azo dye addition. Regarding the anammox process, specific activity decreased down to 58% after 12 days of operation with continuous feeding of 50 mg(orange)/L. However, the anammox activity was completely recovered only 54 days after stopping the dye addition in the feeding. Once the biomass was saturated the azo dye adsorption onto the biomass was insignificant in the CSTR for the partial nitritation process fed with 50 mg(orange)/L. However, in the SBR the absorption was determined as 6.4 mg(orange)/g volatile suspended solids. No biological decolorization was observed in both processes.



Donoso, R., LeivaNovoa, P., Zuniga, A., Timmermann, T., RecabarrenGajardo, G., & Gonzalez, B. (2017). Biochemical and Genetic Bases of Indole3Acetic Acid (Auxin Phytohormone) Degradation by the PlantGrowthPromoting Rhizobacterium Paraburkholderia phytofirmans PsJN. Appl. Environ. Microbiol., 83(1), 20 pp.
Abstract: Several bacteria use the plant hormone indole3acetic acid (IAA) as a sole carbon and energy source. A cluster of genes (named iac) encoding IAA degradation has been reported in Pseudomonas putida 1290, but the functions of these genes are not completely understood. The plantgrowthpromoting rhizobacterium Paraburkholderia phytofirmans PsJN harbors iac gene homologues in its genome, but with a different gene organization and context than those of P. putida 1290. The iac gene functions enable P. phytofirmans to use IAA as a sole carbon and energy source. Employing a heterologous expression system approach, P. phytofirmans iac genes with previously undescribed functions were associated with specific biochemical steps. In addition, two uncharacterized genes, previously unreported in P. putida and found to be related to major facilitator and tautomerase superfamilies, are involved in removal of an IAA metabolite called dioxindole3acetate. Similar to the case in strain 1290, IAA degradation proceeds through catechol as intermediate, which is subsequently degraded by orthoring cleavage. A putative twocomponent regulatory system and a LysRtype regulator, which apparently respond to IAA and dioxindole3acetate, respectively, are involved in iac gene regulation in P. phytofirmans. These results provide new insights about unknown gene functions and complex regulatory mechanisms in IAA bacterial catabolism. IMPORTANCE This study describes indole3acetic acid (auxin phytohormone) degradation in the wellknown betaproteobacterium P. phytofirmans PsJN and comprises a complete description of genes, some of them with previously unreported functions, and the general basis of their gene regulation. This work contributes to the understanding of how beneficial bacteria interact with plants, helping them to grow and/or to resist environmental stresses, through a complex set of molecular signals, in this case through degradation of a highly relevant plant hormone.

