
Contreras, J. P., Bosch, P., Varas, M., & Basso, F. (2020). A New Genetic Algorithm Encoding for Coalition Structure Generation Problems. Math. Probl. Eng., 2020, 13 pp.
Abstract: Genetic algorithms have proved to be a useful improvement heuristic for tackling several combinatorial problems, including the coalition structure generation problem. In this case, the focus lies on selecting the best partition from a discrete set. A relevant issue when designing a Genetic algorithm for coalition structure generation problems is to choose a proper genetic encoding that enables an efficient computational implementation. In this paper, we present a novel hybrid encoding, and we compare its performance against several genetic encoding proposed in the literature. We show that even in difficult instances of the coalition structure generation problem, the proposed approach is a competitive alternative to obtaining good quality solutions in reasonable computing times. Furthermore, we also show that the encoding relevance increases as the number of players increases.



NorambuenaContreras, J., ArteagaPerez, L. E., GuadarramaLezama, A. Y., Briones, R., Vivanco, J. F., & GonzalezTorre, I. (2020). Microencapsulated BioBased Rejuvenators for the SelfHealing of Bituminous Materials. Materials, 13(6), 16 pp.
Abstract: Asphalt selfhealing by encapsulated rejuvenating agents is considered a revolutionary technology for the autonomic crackhealing of aged asphalt pavements. This paper aims to explore the use of BioOil (BO) obtained from liquefied agricultural biomass waste as a biobased encapsulated rejuvenating agent for selfhealing of bituminous materials. Novel BO capsules were synthesized using two simple dripping methods through dropping funnel and syringe pump devices, where the BO agent was microencapsulated by external ionic gelation in a biopolymer matrix of sodium alginate. Size, surface aspect, and elemental composition of the BO capsules were characterized by optical and scanning electron microscopy and energydispersive Xray spectroscopy. Thermal stability and chemical properties of BO capsules and their components were assessed through thermogravimetric analysis (TGADTG) and FourierTransform Infrared spectroscopy (FTIRATR). The mechanical behavior of the capsules was evaluated by compressive and lowload microindentation tests. The selfhealing efficiency over time of BO as a rejuvenating agent in cracked bitumen samples was quantified by fluorescence microscopy. Main results showed that the BO capsules presented an adequate morphology for the asphalt selfhealing application, with good thermal stability and physicalchemical properties. It was also proven that the BO can diffuse in the bitumen reducing the viscosity and consequently selfhealing the open microcracks.



Goles, E., Lobos, F., Ruz, G. A., & Sene, S. (2020). Attractor landscapes in Boolean networks with firing memory: a theoretical study applied to genetic networks. Nat. Comput., to appear, 25 pp.
Abstract: In this paper we study the dynamical behavior of Boolean networks with firing memory, namely Boolean networks whose vertices are updated synchronously depending on their proper Boolean local transition functions so that each vertex remains at its firing state a finite number of steps. We prove in particular that these networks have the same computational power than the classical ones, i.e. any Boolean network with firing memory composed of m vertices can be simulated by a Boolean network by adding vertices. We also prove general results on specific classes of networks. For instance, we show that the existence of at least one delay greater than 1 in disjunctive networks makes such networks have only fixed points as attractors. Moreover, for arbitrary networks composed of two vertices, we characterize the delay phase space, i.e. the delay values such that networks admits limit cycles or fixed points. Finally, we analyze two classical biological models by introducing delays: the model of the immune control of the lambda\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{69pt} \begin{document}$$\lambda $$\end{document}phage and that of the genetic control of the floral morphogenesis of the plant Arabidopsis thaliana.



Reus, L. (2020). Efficient selection of copper sales contracts for small and mediumsized mining. Manag. Decis. Econ., 41(4), 624–630.
Abstract: The purpose of this study is to generate efficient policies for the selection and postponement of copper sales contracts by a mining company. To do so, it uses a twostage stochastic programming model that determines solutions considering different contract types, random prices, and risk aversion. The results show how it is possible for the selection to involve the lowest risk possible for different revenue levels required. During a period of high price volatility, an efficient solution may deliver an increase in monthly revenue of US$210,000 for a mining company that produces 50,000 tons per year, without any additional risk.



Ugalde, D., LopezGarcia, D., & Parra, P. F. (2020). Fragilitybased analysis of the influence of effective stiffness of reinforced concrete members in shear wall buildings. Bull. Earthq. Eng., 18(5), 2061–2082.
Abstract: When modeling RC shear wall buildings for seismic analysis there is little consensus in the literature on the appropriate value of the wall effective shear stiffness (GA(eff)) and the slab effective bending stiffness (EIeff). A probabilistic analysis based on fragility curves is a robust technique to assess the influence of these parameters on the expected seismic performance, but such studies are scarce because they require computationally expensive analysis such as Incremental Dynamic Analysis (IDA). In this paper, fragility curves are developed following the recently introduced SPO2FRAG procedure, a simplified methodology that does not require IDA but the computationally more affordable incremental static (pushover) analysis. The fragility curves provided by SPO2FRAG are used to evaluate the influence of the values of GA(eff) and EIeff on the analytical seismic response of full 3D nonlinear models of two actual (and representative) residential wall buildings of 17 and 26 stories located in Santiago (Chile). The accuracy of SPO2FRAG is also evaluated through comparisons with empirical fragilities.



Sanchez, R., & NietoJimenez, C. (2020). Uso de dispositivos digitales en el seguimiento de un Trail Runner. Estudio de caso (Use of digital devices to follow a Trail Runner. Case study). Retos, 38, 582–586.
Abstract: The aim of this study is to describe a tracking methodology for a Trail Running (TR) athlete during five years through the capture of data from digital devices, associating the race pace and speed with the terrain slope. The trajectories generated by the global positioning system (GPS) were obtained from the Strava platform. From this information, measurements of horizontal distance, elevation gain, slope, horizontal speed, and vertical speed are made. In order to analyze the entire data spectrum the Tobler model was calibrated using a quantile regression. For each training week data from 8 previous weeks was used, and model parameters were extracted for each decile, P0: minimum rhythm; m1: critical angle, C + (relative cost of running uphill) and C(relative cost of running downhill). We conclude that capturing daily data through digital devices is a useful way to obtain information on the association between race pace and slope. A quantile regression model could be useful for the design of training programs for a TR athlete.



Dorval, P., Talens, G. J. J., Otten, G. P. P. L., Brahm, R., Jordan, A., Torres, P., et al. (2020). MASCARA4 b/bRing1 b: A retrograde hot Jupiter around a bright Atype star. Astron. Astrophys., 635, 10 pp.
Abstract: Context. The Multisite AllSky CAmeRA (MASCARA) and bRing are both photometric groundbased instruments with multiple stations that rely on interline chargecoupled devices with widefield lenses to monitor bright stars in the local sky for variability. MASCARA has already discovered several planets in the northern sky, which are among the brightest known transiting hot Jupiter systems. Aims. In this paper, we aim to characterize a transiting planetary candidate in the southern skies found in the combined MASCARA and bRing data sets of HD 85628, an A7V star of V = 8.2 mag at a distance 172 pc, to establish its planetary nature. Methods. The candidate was originally detected in data obtained jointly with the MASCARA and bRing instruments using a Box LeastSquare search for transit events. Further photometry was taken by the 0.7 m ChileanHungarian Automated Telescope (CHAT), and radial velocity measurements with the Fiber Dual Echelle Optical Spectrograph on the European Southern Observatory 1.0 m Telescope. Highresolution spectra during a transit were taken with the CTIO highresolution spectrometer (CHIRON) on the Small and Moderate Aperture Research Telescope System 1.5 m telescope to target the Doppler shadow of the candidate. Results. We confirm the existence of a hot Jupiter transiting the bright A7V star HD 85628, which we codesignate as MASCARA4b and bRing1b. It is in an orbit of 2.824 days, with an estimated planet radius of 1.53(0.04)(+0.07) RJup and an estimated planet mass of 3.1 +/ 0.9 MJup, putting it well within the planetary regime. The CHAT observations show a partial transit, reducing the probability that the transit was around a faint background star. The CHIRON observations show a clear Doppler shadow, implying that the transiting object is in a retrograde orbit with lambda = 244.9(3.6)(+2.7)degrees. The planet orbits at a distance of 0.047 +/ 0.004 AU from the star and has a zeroalbedo equilibrium temperature of 2100 +/ 100 K. In addition, we find that HD 85628 has a previously unreported stellar companion star in the Gaia DR2 data demonstrating common proper motion and parallax at 4.3 '' separation (projected separation similar to 740 AU), and with absolute magnitude consistent with being a K/M dwarf. Conclusions. MASCARA4 b/bRing1 b is the brightest transiting hot Jupiter known to date in a retrograde orbit. It further confirms that planets in nearpolar and retrograde orbits are more common around earlytype stars. Due to its high apparent brightness and short orbital period, the system is particularly well suited for further atmospheric characterization.



MontalvaMedel, M., Rica, S., & Urbina, F. (2020). Phase space classification of an Ising cellular automaton: The Q2R model. Chaos Solitons Fractals, 133, 14 pp.
Abstract: An exact classification of the different dynamical behaviors that exhibits the phase space of a reversible and conservative cellular automaton, the socalled Q2R model, is shown in this paper. Q2R is a cellular automaton which is a dynamical variation of the Ising model in statistical physics and whose space of configurations grows exponentially with the system size. As a consequence of the intrinsic reversibility of the model, the phase space is composed only by configurations that belong to a fixed point or a cycle. In this work, we classify them in four types accordingly to well differentiated topological characteristics. Three of them which we call of type SI, SII, and SIII share a symmetry property, while the fourth, which we call of type AS does not. Specifically, we prove that any configuration of Q2R belongs to one of the four previous types of cycles. Moreover, at a combinatorial level, we can determine the number of cycles for some small periods which are almost always present in the Q2R. Finally, we provide a general overview of the resulting decomposition of the arbitrary size Q2R phase space and, in addition, we realize an exhaustive study of a small Ising system (4 x 4) which is thoroughly analyzed under this new framework, and where simple mathematical tools are introduced in order to have a more direct understanding of the Q2R dynamics and to rediscover known properties like the energy conservation. (C) 2020 Elsevier Ltd. All rights reserved.



Jordan, A., Brahm, R., Espinoza, N., Henning, T., Jones, M. I., Kossakowski, D., et al. (2020). TOI677b: A Warm Jupiter (P=11.2 days) on an Eccentric Orbit Transiting a Late Ftype Star. Astron. J., 159(4), 10 pp.
Abstract: We report the discovery of TOI677.b, first identified as a candidate in light curves obtained within Sectors 9 and 10 of the Transiting Exoplanet Survey Satellite (TESS) mission and confirmed with radial velocities. TOI677.b has a mass of Mp = 1.236(0.067)(+0.069) MJ, a radius of RP = 1.170 +/ 0.03 RJ, and orbits its bright host star (V=.9.8 mag) with an orbital period of 11.23660 +/ 0.00011 d, on an eccentric orbit with e = 0.435 +/ 0.024. The host star has a mass of Mstar = 1.181 +/ 0.058 Mcircle dot, a radius of R. = 1.28(0.03)(+0.03) Rcircle dot, an age of 2.92(0.73)(+0.80) Gyr and solar metallicity, properties consistent with a mainsequence lateF star with Teff = 6295 +/ 77 K. We find evidence in the radial velocity measurements of a secondary longterm signal, which could be due to an outer companion. The TOI677.b system is a wellsuited target for RossiterMclaughlin observations that can constrain migration mechanisms of closein giant planets.



ColiniBaldeschi, R., Cominetti, R., Mertikopoulos, P., & Scarsini, M. (2020). When Is Selfish Routing Bad? The Price of Anarchy in Light and Heavy Traffic. Oper. Res., 68(2), 411–434.
Abstract: This paper examines the behavior of the price of anarchy as a function of the traffic inflow in nonatomic congestion games with multiple origin/destination (O/D) pairs. Empirical studies in realworld networks show that the price of anarchy is close to 1 in both light and heavy traffic, thus raising the following question: can these observations be justified theoretically? We first show that this is not always the case: the price of anarchy may remain a positive distance away from 1 for all values of the traffic inflow, even in simple threelink networks with a single O/D pair and smooth, convex costs. On the other hand, for a large class of cost functions (including all polynomials) and inflow patterns, the price of anarchy does converge to 1 in both heavy and light traffic, irrespective of the network topology and the number of O/D pairs in the network. We also examine the rate of convergence of the price of anarchy, and we show that it follows a power law whose degree can be computed explicitly when the network's cost functions are polynomials.



Aylwin, R., JerezHanckes, C., & Pinto, J. (2020). On the Properties of Quasiperiodic Boundary Integral Operators for the Helmholtz Equation. Integr. Equ. Oper. Theory, 92(2), 41 pp.
Abstract: We study the mapping properties of boundary integral operators arising when solving twodimensional, timeharmonic waves scattered by periodic domains. For domains assumed to be at least Lipschitz regular, we propose a novel explicit representation of Sobolev spaces for quasiperiodic functions that allows for an analysis analogous to that of Helmholtz scattering by bounded objects. Except for RayleighWood frequencies, continuity and coercivity results are derived to prove wellposedness of the associated first kind boundary integral equations.



JerezHanckes, C., & Pinto, J. (2020). Highorder Galerkin method for Helmholtz and Laplace problems on multiple open arcs. Mathematical Modelling and Numerical Analysis, to appear.
Abstract: We present a spectral Galerkin numerical scheme for solving Helmholtz and Laplace prob lems with Dirichlet boundary conditions on a finite collection of open arcs in twodimensional space. A boundary integral method is employed, giving rise to a first kind Fredholm equation whose variational form is discretized using weighted Chebyshev polynomials. Wellposedness of the discrete problems is established as well as algebraic or even exponential convergence rates depending on the regularities of both arcs and excitations. Our numerical experiments show the robustness of the method with respect to number of arcs and large wavenumber range. Moreover, we present a suitable compression algorithm that further accelerates computational times.



Goles, E., & Montealegre, P. (2020). The complexity of the asynchronous prediction of the majority automata. Inform. Comput., to appear.
Abstract: We consider the asynchronous prediction problem for some automaton as the one consisting in determining, given an initial configuration, if there exists a nonzero probability that some selected site changes its state, when the network is updated picking one site at a time uniformly at random. We show that for the majority automaton, the asynchronous prediction problem is in NC in the twodimensional lattice with von Neumann neighborhood. Later, we show that in three or more dimensions the problem is NPComplete.



Alejo, L., Atkinson, J., & Lackner, S. (2020). Looking deeper – exploring hidden patterns in reactor data of Nremoval systems through clustering analysis. Water Sci. Technol., to appear.
Abstract: In this work, clustering analysis of two partial nitritationanammox (PNA) moving bed biofilm reactors (MBBR) containing different types of carrier material was explored for the identification of patterns and operational conditions that may benefit process performance. The systems ran for two years under fluctuations of temperature and organic matter. Ex situ batch activity tests were performed every other week during the operation of these reactors. These datasets and the parameters, which were monitored online and in the laboratory, were combined and analyzed applying clustering analysis to identify nonobvious information regarding the performance of the systems. The initial results were consistent with the literature and from an operational perspective, which allowed the parameters to be explored further. The new information revealed that the oxidation reduction potential (ORP) and the anaerobic ammonium oxidizing bacteria (AnAOB) activity correlated well. ORP also dropped when the reactors were exposed to real wastewater (presence of organic matter). Moreover, operating conditions during nitrite accumulation were identified through clustering, and also revealed inhibition of anammox bacteria already at low nitrite concentrations.



Ruivo, E. L. P., de Oliveira, P. P. B., MontalvaMedel, M., & Perrot, K. (2020). Maximum sensitivity to update schedules of elementary cellular automata over infinite configurations. Information and Computation, to appear.



Villacres, J., ArevaloRamirez, T., Fuentes, A., Reszka, P., & Cheein, F. A. (2019). Foliar Moisture Content from the Spectral Signature for Wildfire Risk Assessments in ValparaisoChile. Sensors, 19(24), 17 pp.
Abstract: Fuel moisture content (FMC) proved to be one of the most relevant parameters for controlling fire behavior and risk, particularly at the wildlandurban interface (WUI). Data relating FMC to spectral indexes for different species are an important requirement identified by the wildfire safety community. In Valparaiso, the WUI is mainly composed of Eucalyptus Globulus and Pinus Radiatacommonly found in Mediterranean WUI areaswhich represent the 97.51% of the forests plantation inventory. In this work we study the spectral signature of these species under different levels of FMC. In particular, we analyze the behavior of the spectral reflectance per each species at five dehydration stages, obtaining eighteen spectral indexes related to water content and, for Eucalyptus Globulus, the area of each leaveassociated with the water contentis also computed. As the main outcome of this research, we provide a validated linear regression model associated with each spectral index and the fuel moisture content and moisture loss, per each species studied.



Guzman, R., Harrison, R., Abarca, N., & Villena, M. G. (2020). A gametheoretic model of reciprocity and trust that incorporates personality traits. J. Behav. Exp. Econ., 84, 11 pp.
Abstract: We propose a gametheoretic model of reciprocity and trust that incorporates personality traits. In the model, positive and negative reciprocity are “reciprocal preferences:” parameters of heterogeneous utility functions that take into account the material welfare of others (positively if they have been kind, negatively if they have been hostile). Trust, on the other hand, is an individual bias that distorts probabilistic beliefs about the trustworthiness of others. Unlike typical gametheoretic models, our model provides an explanation for the heterogeneity of preferences and probabilistic beliefs: a person's personality traits determine both the parameters of his utility function and the magnitude of his beleif bias. We tested the model experimentally. Subjects completed a psychometric questionnaire that measures three personality traits: positive reciprocity, negative reciprocity, and trust. Subsequently, they played a sequential prisoner's dilemma with random rematching and payoffs changing from round to round. From the subjects' psychometric scores and game behaviors we inferred the relationship between reciprocal preferences, belief biases, and personality. The results confirmed the hypotheses of the model.



Diaz, G., Munoz, F. D., & Moreno, R. (2020). Equilibrium Analysis of a Tax on Carbon Emissions with Passthrough Restrictions and Sidepayment Rules. Energy J., 41(2), 93–122.
Abstract: Chile was the first country in Latin America to impose a tax on carbonemitting electricity generators. However, the current regulation does not allow firms to include emission charges as costs for the dispatch and pricing of electricity in real time. The regulation also includes sidepayment rules to reduce the economic losses of some carbonemitting generating units. In this paper we develop an equilibrium model with endogenous investments in generation capacity to quantify the longrun economic inefficiencies of an emissions policy with such features in a competitive setting. We benchmark this policy against a standard tax on carbon emissions and a capandtrade program. Our results indicate that a carbon tax with such features can, at best, yield some reductions in carbon emissions at a much higher cost than standard emission policies. These findings highlight the critical importance of promoting shortrun efficiency by pricing carbon emissions in the spot market in order to incentivize efficient investments in generating capacity in the long run.



Alcaino, P., SantaMaria, H., MagnaVerdugo, C., & Lopez, L. (2020). Experimental fastassessment of postfire residual strength of reinforced concrete frame buildings based on nondestructive tests. Constr. Build. Mater., 234, 10 pp.
Abstract: Assessment of the residual strength of reinforced concrete buildings subjected to fire is a problem that requires fast and sufficiently reliable resolution, necessary for the action of firefighters, forensic fire investigation, and structural assessment of postfire condition of the building to take place. In all cases safety and integrity of firefighters and researchers can be at risk, and it is necessary to have rapidly and sufficiently reliable information in order to choose whether to enter freely, to enter with caution, or simply do not enter to the burned structure. This required prompt assessment gives no time or background to develop mathematical models of the structure and damage propagation. This work presents an experimental methodology for a fast assessment of postfire residual strength of reinforced concrete frame buildings based on the high correlation between the loss of strength and nondestructive test results of frame concrete elements subjected to fire action. (C) 2019 Elsevier Ltd. All rights reserved.



Mondschein, S., Yankovic, N., & Matus, O. (2020). The Challenges of Administering a New Treatment: The Case of Direct Acting Antivirals for Hepatitis C Virus. Public Health, to appear.

