
Baselli, G., Contreras, F., Lillo, M., Marin, M., & Carrasco, R. A. (2020). Optimal decisions for salvage logging after wildfires. OmegaInt. J. Manage. Sci., 96, 9 pp.
Abstract: Strategic, tactical, and operational harvesting plans for the forestry and logging industry have been widely studied for more than 60 years. Many different settings and specific constraints due to legal, environmental, and operational requirements have been modeled, improving the performance of the harvesting process significantly. During the summer of 2017, Chile suffered from the most massive wildfires in its history, affecting almost half a million hectares, of which nearly half were forests owned by medium and small forestry companies. Some of the stands were burned by intense crown fires, which always spread fast, that burned the foliage and outer layer of the bark but left standing dead trees that could be salvage harvested before insect and decay processes rendered them unusable for commercial purposes. Unlike the typical operational programming models studied in the past, in this setting, companies can make insurance claims on part or all of the burnt forest, whereas the rest of the forest needs to be harvested before it loses its value. This problem is known as the salvage logging problem. The issue also has an important social component when considering medium and small forestry and logging companies: most of their personnel come from local communities, which have already been affected by the fires. Harvesting part of the remaining forest can allow them to keep their jobs longer and, hopefully, leave the company in a better financial situation if the harvesting areas are correctly selected. In this work, we present a novel mixedinteger optimizationbased approach to support salvage logging decisions, which helps in the configuration of an operationallevel harvesting and workforce assignment plan. Our model takes into account the payment from an insurance claim as well as future income from harvesting the remaining trees. The model also computes an optimal assignment of personnel to the different activities required. The objective is to improve the cash position of the company by the end of the harvest and ensure that the company is paying all its liabilities and maintaining personnel. We show how our model performs compared to the current decisions made by medium and smallsized forestry companies, and we study the specific case of a small forestry company located in Cauquenes, Chile, which used our model to decide its course of action. (C) 2019 Elsevier Ltd. All rights reserved.



Baudin, K., Fusaro, A., Krupa, K., Garnier, J., Rica, S., Millot, G., et al. (2020). Classical RayleighJeans Condensation of Light Waves: Observation and Thermodynamic Characterization. Phys. Rev. Lett., 125(24), 244101.
Abstract: Theoretical studies on wave turbulence predict that a purely classical system of random waves can exhibit a process of condensation, which originates in the singularity of the RayleighJeans equilibrium distribution. We report the experimental observation of the transition to condensation of classical optical waves propagating in a multimode fiber, i.e., in a conservative Hamiltonian system without thermal heat bath. In contrast to conventional selforganization processes featured by the nonequilibrium formation of nonlinear coherent structures (solitons, vortices, ...), here the selforganization originates in the equilibrium RayleighJeans statistics of classical waves. The experimental results show that the chemical potential reaches the lowest energy level at the transition to condensation, which leads to the macroscopic population of the fundamental mode of the optical fiber. The nearfield and farfield measurements of the condensate fraction across the transition to condensation are in quantitative agreement with the RayleighJeans theory. The thermodynamics of classical wave condensation reveals that the heat capacity takes a constant value in the condensed state and tends to vanish above the transition in the normal state. Our experiments provide the first demonstration of a coherent phenomenon of selforganization that is exclusively driven by optical thermalization toward the RayleighJeans equilibrium.



Becker, F., Montealecre, P., Rapaport, I., & Todinca, I. (2020). The Impact Of Locality In The Broadcast Congested Clique Model. SIAM Discret. Math., 34(1), 682–700.
Abstract: The broadcast congested clique model (BCLIQUE) is a messagepassing model of distributed computation where n nodes communicate with each other in synchronous rounds. First, in this paper we prove that there is a oneround, deterministic algorithm that reconstructs the input graph G if the graph is ddegenerate, and rejects otherwise, using bandwidth b = O(d . log n). Then, we introduce a new parameter to the model. We study the situation where the nodes, initially, instead of knowing their immediate neighbors, know their neighborhood up to a fixed radius r. In this new framework, denoted BCLIQuE[r], we study the problem of detecting, in G, an induced cycle of length at most k (CYCLE <= k) and the problem of detecting an induced cycle of length at least k +1 (CYCLE>k). We give upper and lower bounds. We show that if each node is allowed to see up to distance r = left perpendicular k/2 right perpendicular + 1, then a polylogarithmic bandwidth is sufficient for solving CYCLE>k with only two rounds. Nevertheless, if nodes were allowed to see up to distance r = left perpendicular k/3 right perpendicular, then any oneround algorithm that solves CYCLE>k needs the bandwidth b to be at least Omega(n/ log n). We also show the existence of a oneround, deterministic BCLIQUE algorithm that solves CYCLE <= k with bandwitdh b = O(n(1/left perpendicular k/2 right perpendicular). log n). On the negative side, we prove that, if epsilon <= 1/3 and 0 < r <= k/4, then any epsilonerror, Rround, bbandwidth algorithm in the BCLIQUE[r] model that solves problem CYCLE(<= k )satisfies R . b = Omega(n(1/left perpendicular k/2 right perpendicular)).



Bertossi, L., & Geerts, F. (2020). Data Quality and Explainable AI. ACM J. Data Inf. Qual., 12(2), 11.
Abstract: In this work, we provide some insights and develop some ideas, with few technical details, about the role of explanations in Data Quality in the context of databased machine learning models (ML). In this direction, there are, as expected, roles for causality, and explainable artificial intelligence. The latter area not only sheds light on the models, but also on the data that support model construction. There is also room for defining, identifying, and explaining errors in data, in particular, in ML, and also for suggesting repair actions. More generally, explanations can be used as a basis for defining dirty data in the context of ML, and measuring or quantifying them. We think dirtiness as relative to the ML task at hand, e.g., classification.



Bertossi, L., & Geerts, F. (2020). Data Quality and Explainable AI. J. Data Inform. Qual., 12(2).



Bertossi, L., Li, J., Schleich, M., Suciu, D., & Vagena, Z. (2020). Causalitybased Explanation of Classification Outcomes. In DEEM'20: Proceedings of the Fourth International Workshop on Data Management for EndtoEnd Machine Learning (Vol. 6, pp. 1–10).



Bottcher, L., Montealegre, P., Goles, E., & Gersbach, H. (2020). Competing activistsPolitical polarization. Physica A, 545, 13 pp.
Abstract: Recent empirical findings suggest that societies have become more polarized in various countries. That is, the median voter of today represents a smaller fraction of society compared to two decades ago and yet, the mechanisms underlying this phenomenon are not fully understood. Since interactions between influential actors ("activists'') and voters play a major role in opinion formation, e.g. through social media, we develop a macroscopic opinion model in which competing activists spread their political ideas in specific groups of society. These ideas spread further to other groups in declining strength. While unilateral spreading shifts the opinion distribution, competition of activists leads to additional phenomena: Small heterogeneities among competing activists cause them to target different groups in society, which amplifies polarization. For moderate heterogeneities, we obtain target cycles and further amplification of polarization. In such cycles, the stronger activist differentiates himself from the weaker one, while the latter aims to imitate the stronger activist. (C) 2019 Elsevier B.V. All rights reserved.



Bouma, L. G., Hartman, J. D., Brahm, R., Evans, P., Collins, K. A., Zhou, G., et al. (2020). Cluster Difference Imaging Photometric Survey. II. TOI 837: A Young Validated Planet in IC 2602. Astron. J., 160(5), 20 pp.
Abstract: We report the discovery of TOI 837b and its validation as a transiting planet. We characterize the system using data from the NASA Transiting Exoplanet Survey Satellite mission, the ESA Gaia mission, groundbased photometry from El Sauce and ASTEP400, and spectroscopy from CHIRON, FEROS, and Veloce. We find that TOI 837 is a T = 9.9 mag G0/F9 dwarf in the southern open cluster IC 2602. The star and planet are therefore 35(5)(+11) million years old. Combining the transit photometry with a prior on the stellar parameters derived from the cluster colormagnitude diagram, we find that the planet has an orbital period of 8.3 days and is slightly smaller than Jupiter (Rp = 0.77(0.07)(+0.09) RJup). From radial velocity monitoring, we limit Mp sin i to less than 1.20 MJup (3 sigma). The transits either graze or nearly graze the stellar limb. Grazing transits are a cause for concern, as they are often indicative of astrophysical falsepositive scenarios. Our followup data show that such scenarios are unlikely. Our combined multicolor photometry, highresolution imaging, and radial velocities rule out hierarchical eclipsing binary scenarios. Background eclipsing binary scenarios, though limited by speckle imaging, remain a 0.2% possibility. TOI 837b is therefore a validated adolescent exoplanet. The planetary nature of the system can be confirmed or refuted through observations of the stellar obliquity and the planetary mass. Such observations may also improve our understanding of how the physical and orbital properties of exoplanets change in time.



Brahm, R., Nielsen, L. D., Wittenmyer, R. A., Wang, S. H., Rodriguez, J. E., Espinoza, N., et al. (2020). TOI481 b and TOI892 b: Two Longperiod Hot Jupiters from the Transiting Exoplanet Survey Satellite. Astron. J., 160(5), 14 pp.
Abstract: We present the discovery of two new 10 day period giant planets from the Transiting Exoplanet Survey Satellite mission, whose masses were precisely determined using a wide diversity of groundbased facilities. TOI481.b and TOI892.b have similar radii (0.99.+/.0.01 RJ and 1.07.+/.0.02 RJ, respectively), and orbital periods (10.3311 days and 10.6266 days, respectively), but significantly different masses (1.53.+/.0.03 MJ versus 0.95.+/.0.07 MJ, respectively). Both planets orbit metalrich stars ([Fe H] = + 0.26. 0.05 dex and [Fe H] = +0.24. 0.05 for TOI481 and TOI892, respectively) but at different evolutionary stages. TOI481 is a M*=.1.14.+/.0.02 M., R*=.1.66.+/.0.02 R. Gtype star (Teff = 5735 +/ 72 K), that with an age of 6.7 Gyr, is in the turnoff point of the main sequence. TOI892 on the other hand, is a Ftype dwarf star (Teff = 6261 +/ 80 K), which has a mass of M*=.1.28.+/.0.03 Mcircle dot and a radius of R*=.1.39.+/.0.02 Rcircle dot. TOI481.b and TOI892.b join the scarcely populated region of transiting gas giants with orbital periods longer than 10 days, which is important to constrain theories of the formation and structure of hot Jupiters.



Bunster, C., Gomberoff, A., & Perez, A. (2020). BondiMetznerSachs invariance and electricmagnetic duality. Phys. Rev. D, 101(4), 15 pp.
Abstract: We exhibit a Hamiltonian formulation, both for electromagnetism and gravitation, in which it is not required that the Bondi “news” vanish but only that the incoming news be equal to the outgoing ones. This requirement is implemented by defining the fields on a twosheeted hyperbolic surface, which we term “the hourglass.” It is a spacelike deformation of the complete light cone. On it, one approaches asymptotically (null) past and future infinity while remaining at a fixed (hyperbolic) time, by going to large spatial distances on its two sheets. The Hamiltonian formulation andin particulara conserved angular momentum, can only be constructed if one brings in both the electric and magnetic BondiMetznerSachs (BMS) charges together with their canonically conjugate “memories.” This reveals a close interplay between the BMS and electricmagnetic duality symmetries.



Caerols, H., & Asenjo, F. A. (2020). Estimating the MoontoEarth Radius Ratio with a Smartphone, a Telescope, and an Eclipse. Phys. Teach., 58(7), 497–501.
Abstract: From ancient times, the different features of planets and moons have created a huge interest. Aristarchus was one of the first to study the relative relations among Earth, Moon, and Sun. This interest has remained until today, and therefore it is always relevant to make this knowledge more appealing to the younger generations. Nowadays, smartphone technology has become an important tool to teach physics, and this gives us a huge opportunity to bring science closer to students in a simpler manner. In this work, we show how simple photographs of a partial lunar eclipse are sufficiently good to estimate the ratio between the Moon and Earth radii. After taking the photographs, the procedure for the calculation is straightforward and it can be reproduced easily in a one–hour class



Calderon, F. I., Lozada, A., BorquezParedes, D., Olivares, R., Davalos, E. J., Saavedra, G., et al. (2020). BERAdaptive RMLSA Algorithm for WideArea Flexible Optical Networks. IEEE Access, 8, 128018–128031.
Abstract: Widearea optical networks face significant transmission challenges due to the relentless growth of bandwidth demands experienced nowadays. Network operators must consider the relationship between modulation format and maximum reach for each connection request due to the accumulation of physical layer impairments in optical fiber links, to guarantee a minimum quality of service (QoS) and quality of transmission (QoT) to all connection requests. In this work, we present a BERadaptive solution to solve the routing, modulation format, and spectrum assignment (RMLSA) problem for widearea elastic optical networks. Our main goal is to maximize successful connection requests in widearea networks while choosing modulation formats with the highest efficiency possible. Consequently, our technique uses an adaptive biterrorrate (BER) threshold to achieve communication with the best QoT in the most efficient manner, using the strictest BER value and the modulation format with the smallest bandwidth possible. Additionally, the proposed algorithm relies on 3R regeneration devices to enable longdistances communications if transparent communication cannot be achieved. We assessed our method through simulations for various network conditions, such as the number of regenerators per node, traffic load per user, and BER threshold values. In a scenario without regenerators, the BERAdaptive algorithm performs similarly to the most relaxed fixed BER threshold studied in blocking probability. However, it ensures a higher QoT to most of the connection requests. The proposed algorithm thrives with the use of regenerators, showing the best performance among the studied solutions, enabling longdistance communications with a high QoT and low blocking probability.



Cando, M. A., Hube, M. A., Parra, P. F., & Arteta, C. A. (2020). Effect of stiffness on the seismic performance of code conforming reinforced concrete shear wall buildings. Eng. Struct., 219, 14 pp.
Abstract: This study assesses the effect of the stiffness on the seismic performance of residential shear wall buildings designed according to current Chilean regulations, including DS60 and DS61. Specifically, the paper focuses on the effect of stiffness on the building overstrength, displacement ductility, fragility for Life Safety (LS) and collapse limit states, as well as the probability of achieving these two limits states in 50 years. The seismic performance is assessed for a group of four 20 story residential shear wall buildings archetypes located in Santiago. Walls were modeled using the multiple vertical line element model (MVLEM) with inelastic hysteretic materials for the vertical elements, and a linear elastic shear behavior. Pushover analyses were considered to estimate the buildings overstrength and displacement ductility, while incremental dynamic analyses were per formed to estimate fragility curves. A probabilistic seismic hazard analysis, which considered the seismicity of Chile central zone, was performed to estimate the probability of achieving the two limits states in 50 years. The results show that an increase in the stiffness reduces the chance of exceeding the LS and collapse limit states for the same intensity level. Additionally, the probabilistic seismic hazard analysis shows that, when the stiffness increases, the probability of reaching the LS limit state in 50 years also decreases. Counterintuitively, the probability of collapse in 50 years increases as the stiffness increases, due to the considered seismic hazard and the design requirements. Since society is moving towards resilient structural designs that minimize damage, disruption and economic losses, it is concluded that the performance of reinforced concrete shear wall buildings is improved by increasing the stiffness.



Canessa, E., & Chaigneau, S. E. (2020). Mathematical regularities of data from the property listing task. J. Math. Psychol., 97, 19 pp.
Abstract: To study linguistically coded concepts, researchers often resort to the Property Listing Task (PLT). In a PLT, participants are asked to list properties that describe a concept (e.g., for DOG, subjects may list “is a pet”, “has four legs”, etc.), which are then coded into property types (i.e., superficially dissimilar properties such as “has four legs” and “is a quadruped” may be coded as “four legs”). When the PLT is done for many concepts, researchers obtain Conceptual Properties Norms (CPNs), which are used to study semantic content and as a source of control variables. Though the PLT and CPNs are widely used across psychology, there is a lack of a formal model of the PLT, which would provide better analysis tools. Particularly, nobody has attempted analyzing the PLT's listing process. Thus, in the current work we develop a mathematical description of the PLT. Our analyses indicate that several regularities should be found in the observable data obtained from a PLT. Using data from three different CPNs (from 3 countries and 2 different languages), we show that these regularities do in fact exist and generalize well across different CPNs. Overall, our results suggest that the description of the regularities found in PLT data may be fruitfully used in the study of concepts. (C) 2020 Elsevier Inc. All rights reserved.



Canessa, E., Chaigneau, S. E., Moreno, S., & Lagos, R. (2020). Informational content of cosine and other similarities calculated from highdimensional Conceptual Property Norm data. Cogn. Process., 21, 601–614.
Abstract: To study concepts that are coded in language, researchers often collect lists of conceptual properties produced by human subjects. From these data, different measures can be computed. In particular, interconcept similarity is an important variable used in experimental studies. Among possible similarity measures, the cosine of conceptual property frequency vectors seems to be a de facto standard. However, there is a lack of comparative studies that test the merit of different similarity measures when computed from property frequency data. The current work compares four different similarity measures (cosine, correlation, Euclidean and Chebyshev) and five different types of data structures. To that end, we compared the informational content (i.e., entropy) delivered by each of those 4 x 5 = 20 combinations, and used a clustering procedure as a concrete example of how informational content affects statistical analyses. Our results lead us to conclude that similarity measures computed from lowerdimensional data fare better than those calculated from higherdimensional data, and suggest that researchers should be more aware of data sparseness and dimensionality, and their consequences for statistical analyses.



Carbonnel, C., Romero, M., & Zivny, S. (2020). PointWidth and MaxCSPs. ACM Trans. Algorithms, 16(4), 28 pp.
Abstract: The complexity of (unboundedarity) MaxCSPs under structural restrictions is poorly understood. The two most general hypergraph properties known to ensure tractability of MaxCSPs, betaacyclicity and bounded (incidence) MIMwidth, are incomparable and lead to very different algorithms. We introduce the framework of point decompositions for hypergraphs and use it to derive a new sufficient condition for the tractability of (structurally restricted) MaxCSPs, which generalises both bounded MIMwidth and betaacyclicity. On the way, we give a new characterisation of bounded MIMwidth and discuss other hypergraph properties which are relevant to the complexity of MaxCSPs, such as betahypertreewidth.



Cardenas, C., Guzman, F., Carmona, M., Munoz, C., Nilo, L., Labra, A., et al. (2020). Synthetic Peptides as a Promising Alternative to Control Viral Infections in Atlantic Salmon. Pathogens, 9(8), 600.
Abstract: Viral infections in salmonids represent an ongoing challenge for the aquaculture industry. Two RNA viruses, the infectious pancreatic necrosis virus (IPNV) and the infectious salmon anemia virus (ISAV), have become a latent risk without healing therapies available for either. In this context, antiviral peptides emerge as effective and relatively safe therapeutic molecules. Based on in silico analysis of VP2 protein from IPNV and the RNAdependent RNA polymerase from ISAV, a set of peptides was designed and were chemically synthesized to block selected key events in their corresponding infectivity processes. The peptides were tested in fish cell lines in vitro, and four were selected for decreasing the viral load: peptide GIM182 for IPNV, and peptides GIM535, GIM538 and GIM539 for ISAV. In vivo tests with the IPNV GIM 182 peptide were carried out using Salmo salar fish, showing a significant decrease of viral load, and proving the safety of the peptide for fish. The results indicate that the use of peptides as antiviral agents in disease control might be a viable alternative to explore in aquaculture.`



Carleo, I., Gandolfi, D., Barragan, O., Livingston, J. H., Persson, C. M., Lam, K. W. F., et al. (2020). The Multiplanet System TOI421*. Astron. J., 160(3), 23 pp.
Abstract: We report the discovery of a warm Neptune and a hot subNeptune transiting TOI421 (BD14 1137, TIC 94986319), a bright (V = 9.9) G9 dwarf star in a visual binary system observed by the Transiting Exoplanet Survey Satellite (TESS) space mission in Sectors 5 and 6. We performed groundbased followup observationscomprised of Las Cumbres Observatory Global Telescope transit photometry, NIRC2 adaptive optics imaging, and FIbrefed Echelle Spectrograph, CORALIE, High Accuracy Radial velocity Planet Searcher, High Resolution echelle Spectrometer, and Planet Finder Spectrograph highprecision Doppler measurementsand confirmed the planetary nature of the 16 day transiting candidate announced by the TESS team. We discovered an additional radial velocity signal with a period of five days induced by the presence of a second planet in the system, which we also found to transit its host star. We found that the inner miniNeptune, TOI421 b, has an orbital period of Pb = 5.19672 +/ 0.00049 days, a mass of Mb = 7.17 +/ 0.66 Mcircle plus, and a radius of Rb = Rcircle plus, whereas the outer warm Neptune, TOI421 c, has a period of Pc = 16.06819 +/ 0.00035 days, a mass of Mc = 16.42(1.04)(+1.06)M(circle plus), a radius of Rc = 5.09(0.15)(+0.16)R(circle plus), and a density of rho(c) = 0.685(0.072)(+0.080) cm(3). With its characteristics, the outer planet (rho(c) = 0.685(0.0072)(+0.080) cm(3)) is placed in the intriguing class of the superpuffy miniNeptunes. TOI421 b and TOI421 c are found to be wellsuited for atmospheric characterization. Our atmospheric simulations predict significant Ly alpha transit absorption, due to strong hydrogen escape in both planets, as well as the presence of detectable CH4 in the atmosphere of TOI421 c if equilibrium chemistry is assumed.



Carmichael, T. W., Quinn, S. N., Mustill, A. J., Huang, C., Zhou, G., Persson, C. M., et al. (2020). Two Intermediatemass Transiting Brown Dwarfs from the TESS Mission. Astron. J., 160(1), 15 pp.
Abstract: We report the discovery of two intermediatemass transiting brown dwarfs (BDs), TOI569b and TOI1406b, from NASA's Transiting Exoplanet Survey Satellite mission. TOI569b has an orbital period of P = 6.55604 0.00016 days, a mass of Mb = 64.1 1.9 , and a radius of Rb = 0.75 0.02 . Its host star, TOI569, has a mass of Mstar = 1.21 0.05, a radius of Rstar = 1.47 0.03 dex, and an effective temperature of Teff = 5768 110 K. TOI1406b has an orbital period of P = 10.57415 0.00063 days, a mass of Mb = 46.0 2.7 , and a radius of Rb = 0.86 0.03 . The host star for this BD has a mass of Mstar = 1.18 0.09 a radius of Rstar = 1.35 0.03 dex, and an effective temperature of Teff = 6290 100 K. Both BDs are in circular orbits around their host stars and are older than 3 Gyr based on stellar isochrone models of the stars. TOI569 is one of two slightly evolved stars known to host a transiting BD (the other being KOI415). TOI1406b is one of three known transiting BDs to occupy the mass range of 4050 and one of two to have a circular orbit at a period near 10 days (with the first being KOI205b). Both BDs have reliable ages from stellar isochrones, in addition to their wellconstrained masses and radii, making them particularly valuable as tests for substellar isochrones in the BD massradius diagram.



Carrasco, M., Toledo, P. A., Velazquez, R., & Bruno, O. M. (2020). Automatic Stomatal Segmentation Based on DelaunayRayleigh Frequency Distance. PlantsBasel, 9(11), 1613.
Abstract: The CO2 and water vapor exchange between leaf and atmosphere are relevant for plant physiology. This process is done through the stomata. These structures are fundamental in the study of plants since their properties are linked to the evolutionary process of the plant, as well as its environmental and phytohormonal conditions. Stomatal detection is a complex task due to the noise and morphology of the microscopic images. Although in recent years segmentation algorithms have been developed that automate this process, they all use techniques that explore chromatic characteristics. This research explores a unique feature in plants, which corresponds to the stomatal spatial distribution within the leaf structure. Unlike segmentation techniques based on deep learning tools, we emphasize the search for an optimal threshold level, so that a high percentage of stomata can be detected, independent of the size and shape of the stomata. This last feature has not been reported in the literature, except for those results of geometric structure formation in the salt formation and other biological formations.

